In the Last Walkthrough, you and Detective Nick Valentine got the next clue to locate Kellogg's current location. With the help of Dogmeat and Kellogg's cigar, you found in the secret Room will help you locate him in this Walkthrough Guide for Main Mission 6: Reunions.
Now that you have shown Kellogg's cigar to Dogmeat, he will guide you first to Nick Valentine's location. We must warn you that this is a very lengthy mission so be prepared with your weapons and don't completely be depended on Dogmeat as he is just showing you the way and on the way you need to examine the clues to locate him.
The objective marker you see on Dogmeat will be interrupted several times as this is an indication that you are missing some clue and you need to search the area for San Francisco Sunlight and Bloodied Bandages. For every time the Dogmeat stops you need to search for Kellogg's clue.
After few clues, you need to find an alternative clue so that Dogmeat will take you to Fort Hagen. At the Fort Hagen, take a look at the turrets surrounded the complex so try taking them out quickly with just two shots while you are hiding and take the bonus damage.
Head Left from the building until you reach an underground where there small sets of stairs. From there you will see a couple of ruined and burned cars in the parking lot, again take the stairs and head down towards a room with a dead body on the chair. Keep moving from door to door until you reach the entrance of the Fort Hagen which is just right of the parking ramp.
Once you're inside the Fort Hagen, it's time to search for the clues so get ready to explore and fight with the Synths, but don't you worry we have Nick with us to help us to deal with these. Once you have cleared all the synth and turrets you can start you looting in the Fort Hagen.
After you have finished looting the first set of the Fort Hagen move up and make sure you don't make any noise with your loud weapon as this might alert the other Synths on the floor and they will get ready to take your down. To get rid of them try placing some mines at the doorways and few at the stairs as well. This will allow you to make an easy kill with noise.
Search for all the floor and rooms for the clues you can take for Nick, there is a terminal at Stairwell, but it will only trigger the nearby robot and eventually start shooting the Synths nearby. You can also ask Nick to hack the terminal from the center of the room which will open the a locked cage on the top floor. After the exploration is complete and you need to get back to the original mission objective then go into the elevator and take a trip down a few floors which will take you straight into the Basement.
At the Basement, you will see a turret and few Synths guards patrolling the area. Take them down as per your wish just make sure you don't set any traps along the narrow corridor. After finishing them off go into the room where you saw the turret and from there you can take the stairs and climb down towards Fort Hagen Command Center.
From here get ready to take down all enemies in order to get closer to your target. you will deal with Synths and turrets from the very beginning and even Kellogg is trying to taunt you while you are getting closer to him. you need to keep clearing the enemy waves in each room of the Command Control. Once you made it till the last room you'll find your target who kidnapped your son.
Before you confront Kellogg, just have a look at the First Aid kit on the desk and ammo so the bed. Get into the office and start talking to Kellogg, where he will inform you about his Synths are waiting down. Go ahead and let's get some good armor from there.
It will all different for different users depending on what and how they choose to approach Kellogg, but the end result will be the same where you need to fight him and we recommend to bring some Molotovs to throw behind the desk where he is hiding. OIf you notice that Kellogg will regenerate his health when he gets heavy damage like the Bombs. Take the legendary perk on his gun after killing him and later focus on the remaining Synths.
Before you move ahead just check on the list you need to grab from Kellogg. These three are very much important to progress in the game further os make sure you don't miss out any.
After the Battle is over just walk towards Nick and have a conversation with him and he will ask you to have a word with Piper(the reporter). After Nick, go ahead and climb the steps and take a left at the top to get to the next area and call the elevator. Fast Travel to Dimond City near Public Occurrences office. First make sure you have marked this as your current Objective before heading out. Pepper will be waiting inside the office so head towards his room and Tell him that you need help and also inform about Kellogg's death. Nick will suggest you to visit Doctor Amari at the Memory Den.
For now just agree to their plan and listen carefully to Nick's notes and then tell him that you have already what Nick is looking for. Now you have to decide whom you need to tag along to the next journey. We will be taking Nick and end the conversation. Thus completing the sixth part of the Fallout 4 Walkthrough.
