Best Left Forgotten - Fallout 4 Guide - IGN (2024)

The story quest Best Left Forgotten is a DLC quest that is part of the Far Harbor Walkthrough.

Once you have either completed the test in the Visions in the Fog quest, or blasted your way through the entire base of the Children of Atom, you'll find yourself in The Nucleus - a radioactive submarine dry dock and place of worship.

Gain Access to DiMA’s Terminal

Now inside the Nucleus, you can choose to learn more about your family, talk with the High Confessor Tektus, check out the merchants and healers like The Archemist, Sister Mai, and Brother Kane - or head right up the far end of the main dry dock to the top floor that leads to the command center. A Child of Atom will try and dissuade you from entering, but you can wave her off and enter anyway.

Inside, you’ll find the place on high alert. The passage to the right ends in a dead end, leaving you with a long hall filled with laser tripwires on both sides, tied to three rows of turrets ready to open fire should you or a companion trigger them. Either carefully disarm them one at a time or dodge between them and be on your way.

As you proceed, another turret is waiting as the path curves left, before leading to a hall with barracks - and a Mr. Gutsy with another turret above the far door. Loot the barracks before heading deeper into the cave, where a Protectron waits just before two doors - the left leading to a kitchen with another Protectron, and the far door leading further into the command center.

After heading up some stairs and through another winding corridor, you’ll find one more blockade featuring an Assaultron, Protectron, and two turrets above the wall leading to the main console. Once they’ve been dealt with, access the nearby terminal to open the gate leading to the command console - and check the trunk for loot next to the terminal before heading inside.

The main terminal is offline, and you can just make out the sparking circuit breaker in the gated room beyond. Before you do, note the sealed door to the left of the main terminal. The moment you restore power, the door will open and a very angry Assaultron will burst forth to stop you - better you prepare yourself and perhaps mine the area to leave a trap for the robot.

After flipping the circuit breaker and dealing with the Assaultron (and checking Captain Wabash’s Advanced locked terminal for additional info), interact with the main console and launch Faraday’s program to enter… a very interesting reality.

Retrieve Memory 0V-9AX0 (Memory 1)

Welcome to DiMA’s memories. This sort of matrix-y virtual reality acts as a sort of lemmings/reverse-tower-defense map. Note that you’ll be in a “Simulation” mode while in this world, which is pretty much a limited settlement building state. You’ll need to utilize basic building and re-purposing to solve the puzzles of these memory blocks and unlock DiMA’s memories.

The object of this state is to ensure the little “indexer” bugs can travel all the way to the yellow data stream at the far end, and return to the blue data stream to deposit memory they obtain. You ensure this by placing blocks to fill in gaps in the path, and unlock “firewalls” by allowing the green beams of light to hit the key block in their wall.

Of course, once your indexers start collecting data, a defense system will engage, and small floating orbs will come in and try to destroy the indexers, which you must stop by placing up to five turrets strategically to ensure their survival. Worry not - if an indexer is destroyed, a new one will start over from the beginning - and each indexer carries 20% of the data across, which means five indexers must survive the journey. You can also quit out of the simulation and return at any time to find everything as you’ve left it - and you can’t “die” in the simulation.

• Step One: Move the four lighter colored Code Blocks in your starting area to place them to form a bridge for your indexers to the next area.

• Step Two: To deactivate the firewall, simply remove the lighter colored Code Block stopping the green Decoder Beam from hitting the key point of the firewall. Build a bridge across with some of the Code Blocks in the corner of this area.

• Step Three: To deactivate this firewall, you need to realign the Decoder Relay - a Code Block that takes the Decoder Relay beam and outputs it in another direction. Grab the block and swivel it so that the green face is pointing at the other firewall. Now use the remaining Code Blocks in the corner to build a path to the yellow data stream

• Step Four: As the first of your indexers reach the data stream, sentries will be deployed to stop them. You’ll have 5 turrets of your own to place, so use them strategically, placing them in areas where you see the enemy spawn, like each of the four corners of the map.

Once you’ve gained 100% of the memory file, you’ll gain access to Memory 2 - and can enter it by going through the once yellow but now blue data stream. You’ll also get an audio log of DiMAs thoughts that paint a very troubling picture. It’s only a piece of the puzzle, but you’ll be given the coordinates to a Pop Vim factory that holds the truth of this memory - which you can chase down now, or continue to uncover memories.

Retrieve Memory 0J-2NN8 (Memory 2)

This memory arena looks very different from the previous one, and features a much larger area, with a Decoder Stream connected to a long green tether. There’s also a long hall that leads to a tight corridor ending in a firewall that must be breached.

• Step One: Note the Decoder Stream below you, and hop down and remove the Code Block that is blocking the strem from hitting the green relay that leads it up above near the corridor.

• Step Two: Follow the Decoder Stream and remove the Code Block its hitting, and store the extra Code Blocks nearby. When the stream hits the wall beyond, move the Decoder Relay next to it to face the corridor where the Firewall is, and remove the Code Block to make a window in.

• Step Three: With the first Firewall gone, turn the corner to find a much bigger Firewall blocking the way to the Data Stream. On your left is another Decoder Relay. Grab it and build a pillar where the Decoder Stream ends one tile from the wall to turn it and hit the Firewall’s weak point.

• Step Four: Store the remaining Code Blocks near the Firewall and build a bridge of at least two Code Blocks wide over to the stream. Place your five turrets near both streams, as well as the long open path on the other side of the small enclosed corridor.

After gaining 100% of the memory file, you’ll gain access to Memory 3, as well as an audio log revealing another of DiMA’s forgotten secrets - the location of the key to trigger the nuclear detonation of the submarine in The Nucleus, which you can pursue now, or hold off until later.

Retrieve Memory 0H-3X0P (Memory 3)

This memory arena is also a new one, and features a wall you’ll have to tear down, and many multiple level areas you’ll have to traverse above while your indexers go along below.

• Step One: disassemble the wall in front of you and build a bridge for your indexers to cross. Doing so will allow the Decoder Stream to hit the first Firewall and allow you passage across as well.

• Step Two: With a firewall on either side, and no Decoder Relay to speak of, you’ll need to head to higher ground. Look above the Firewall on the left to spy a small chamber with the Decoder Relay you need, and use the Code Block stairs to get up - making a bridge out of extra blocks if you have to. Store all the Code Blocks in this alcove and take the Decoder Relay too.

• Step Three: Back in the middle of the open area, place another Code Block on top of the single block already there, and aim the Decoder Relay back at the Firewall on the left to disrupt it. Now clear out the Code Blocks and store the second relay, while moving the pillar with the first relay two spaces over to hit the green relay wall to send the beam above, dissipating the next Firewall.

• Step Four: Use the Code Blocks you’ve been storing to build a bridge for your indexers to lead them down the long enclosed corridor before it turns left to one last Firewall.

• Step Five: Climb up above the enclosed corridor to spot the weak point of the Firewall, and build a second pillar with the second Decoder Relay and aim it at the firewall three blocks up. Doing so will erode the last Firewall between you and the Data Stream.

• Step Six. With the Firewalls gone, disassemble the pillars for extra Code Blocks so that you can build a bridge of at least two blocks wide over to the Data Stream. With the indexers on their way, set up turrets near the two ends of the enclosed corridor, and in the large area before the bridge leading back to your home base.

With 100% of the memory file, the path to Memory 4 will be open. The audio log of his memories will indicate a very disturbing contingency plan for the people of Far Harbor, should they get out of land, and you’ll be given the location of a kill switch code for the windmill generator that powers Far Harbor, as well as the generator’s location. You can make the trek to find it now, or continue on hunting for memories.

Retrieve Memory 0Z-7A4K (Memory 4)

Memory 4 is a much more complex level featuring large Firewalls that encompass multiple sides, as well as pathways that only the indexers can take, and multiple Decoder Relay walls.

• Step One: Noting the Decoder Stream coming from below, check the right alcove and store all the Data Blocks and the one Decoder Relay. Now use the Data Blocks to build a pillar three blocks high next to the Data Stream, and attach the relay to the side of the pillar facing the Firewall on the left and disable it.

• Step Two: Collect and store all the other Data Blocks in the now uncovered alcove, as well as a second Decoder Relay. With two of them as your disposal, lower the first Decoder Relay by one block, and aim it towards the Firewall. However the weak point is on a side wall, so build out a platform of Data Blocks on block high above the raised platform, and send the relay at the side wall to deactivate the large Firewall.

• Step Three: With the Firewall gone, collect the Data Block Pillars and Relays. Your next step is to connect the Decoder Stream to the large Relay wall that starts below you, so head right down a stairway to the bottom level to find where the beam originates. Place two Data Blocks going toward the beam until it catches, then place a Decoder Relay on the second block to send it towards the far end from where you came. As it crosses the broken walkway, look right to find the entry point for the Relay wall, and place a single Data Block on the edge of the broken walkway where you can then place the second Relay facing the wall, allowing it to relay back up top and into the remaining Firewall’s weak point.

• Step Four: Collect the Data Blocks you used to build pathways, and return to the main walkway where your indexers wait - and build a path through the broken sections at least two spaces wide for better movement. As your indexers near the Data Stream, get ready to place your five turrets. Check where the enemies spawn near the Data Stream, and along the long pathway leading back.

At 100% of the memory collected, you’ll gain access to the last memory file, as well as a very telling audio log of a surprising altercation between one Nick Valentine, and DiMA.

Retrieve Memory 0Y-8K7D (Memory 5)

The last memory area is the most complex, even with the Data Stream so close yet so far away, you’ll need to reach and tweak each little island in the area to route the Decoder Relays back to the main firewall.

• Step One: Begin by storing every last Data Block place around the edges of the main platform, and then build a bridge to the center island where a large pyramid-like structure has a Decoder Stream appearing from the ceiling.

• Step Two: Once at the pyramid, store the Data Blocks forming doors on all sides of the structure, and take the four blocks on the top, and those around the middle as well, leaving a lone Decoder Relay in the middle. Since the Relay can’t reach the main firewall blocking the Data Stream, you’ll have to instead place the Relay atop two Data Blocks, and face it opposite the way it used to face, towards a side with another Firewall (not the one opposite the Data Stream).

• Step Three: With the firewall down, build a new bridge leading to the island with four pillars, and store both the new Decoder Relay, as well as the Data Blocks that make up the four pillars. Then build another bridge to the lone island back towards the Data Stream that does not have a Firewall, and store all the Data Blocks you can find, and take back the bridge as you return to the island with four pillars.

• Step Four: With the Decoder beam crossing the island, build a pillar three Data Blocks high, and place a Relay on top pointing at the far island with the Firewall to deactivate it. Build a bridge out to the tiny island to grab the lone Decoder Relay, and build a pillar of three Data Blocks that the Relay can sit on top of, and aim it at the far island that has a wall with a Data Block you can soon remove

• Step Five: Return to the center island, and build a bridge the island with the walls opposite the Data Stream. Remove all the single Data Blocks at various points of the islands walls, including the one from the middle of the plus sign, and both walls so that the Decoder Stream can pass straight through the island and into the Decoder wall that outputs from the bottom into an island higher up.

• Step Six: Return back to your starting blue Data Stream, and now build a bridge to the remaining island to the side of the Firewall island, where you can see several block stairs. Store the Decoder Relay when you get across, and climb up the stairs until you reach a platform with another Firewall, and more stairs opposite it. Climb the last stairs and begin removing the Data Blocks that form a door to where the Decoder Stream is outputting.

• Step Seven: In the small room with the Decoder Stream, drop down a level and remove the Data Blocks on all sides, then place a Decoder Relay over the opening and direct it back at the Firewall. Now you can grab the now unprotected Decoder Relay, as well as the last one above it, which you can build a bridge to.

• Step Eight: Return to the small room and take back the Decoder Relay. Return to the first platform where you obtained the Decoder Relay after crossing the bridge from the Data Stream. Look at the last Firewall and note that the weak point is exactly three blocks above ground level where you are. Now look back at the Decoder Beam that’s across from a set of stairs that ends exactly three blocks above your current position. Build a bridge out to the beam and place one relay going back to that first platform you were at. Return to that platform, and place two Data Blocks at the very end of the platform, and a Decoder Relay pointing towards the blue data stream - it should pass right between the blue and yellow Data Streams. All that’s left is to make one last pillar and redirect the Decoder Stream a final time at the last Firewall, and build a bridge, while placing turrets all around the Data Streams.

With 100% of the memory yours, all of DiMA’s lost memories will be obtained, and you’ll be privy to the location of several Marine Armor Shipments that are extremely well-crafted and worth going to find, so long as you’re prepared to do some offshore diving.

What you do now will change the shape of this long mysterious case file. Whatever you end up doing, it is necessary that you locate each of his secrets: The Nuclear Launch Key, the Secret Medical Facility, and the Wind Farm Kill Switch Code. They can be found in any order you wish, and once you have the intel, you’ll have to decide what to do with it.

Memory 5 quick trick

This guide shows how to quickly and easily complete level 5 of Dima's Memories, (probably making hardest level the easiest):

Note: If you’ve had Nick Valentine tagging along, now might be a good time to have that conversation about his relationship with DiMA, since you now have even more proof of a connection with the new audio tape you’ve gained from his memories. He’ll appreciate the help, and you can give him a nudge in what to do regarding this newfound knowledge.