Find the Treasures of Jamaica Plain

Find the Treasures of Jamaica Plain is a miscellaneous quest in Fallout 4.

Detailed walkthrough
Find the Treasures of Jamaica Plain is a miscellaneous quest triggered by finding Hadrian's body, which appears randomly throughout the Commonwealth and listening to Hadrian's invitation located in his inventory. It can also be triggered by finding and reading a Jamaica Plain flyer, found in various places throughout the Commonwealth or through the Information desk terminal located in the Boston Airport ruins. Alternatively, one can simply locate Jamaica Plain and enter the town hall's basement without having actually triggered the quest.

Upon discovering Jamaica Plain, the Sole Survivor will need to locate the Jamaica Plain Town Hall basement. The town hall is found in the southern portion of the town and is easily visible as it's one of the biggest and most distinct buildings in the area. The basement is to the left of the main entrance and down a set of stairs.

Jamaica Plain itself is swarming with feral ghouls. Several of them may charge the player character at once. Clearing the town of feral ghouls is not a prerequisite for entering the basement, however.

In the basement, the player character will be able to quickly make their way to a small hall filled with laser trip wires. Activating one of them will cause several turrets located near the end of the hall to begin firing in their defense of the "treasures" located within. These trip wires can be disarmed one by one, each giving the player character crystal, steel and fiber optics. They can also be disarmed with the computer panel in front of the hall by using the Jamaica Plain mayor's ID, which is found on a dead body inside the church across from the town hall. To obtain it, one would need to access the church through the roof that is connected to the next building, as the ground entrance is chained from the inside.

Alternatively, one has the option to pick the lock on a Master-locked door to bypass the tripwires. Once they go through the short corridor that follows, the door to the treasure room is locked by a Novice terminal in the center of the room. If the player fails to hack the terminal on the first try (or aborts their hacking attempt), the two Protectrons in the room will activate and become hostile. To avoid this, the player can alternatively find the terminal password on the corpse of a mercenary named Sal, located in an office on the 2nd floor of the Town Hall.

Once through the door guarded by the trip wires, traveling through the remainder of the basement and a few more doors (or the shortcut) will lead to the "treasure" of Jamaica Plain, containing the 2076 World Series baseball bat and many unique pre-War items not found elsewhere in the game. There are also some holotapes on the table immediately within the room, such as the Treasures inventory holotape, which lists items that are found in the treasure vault and the reasons for it existing. However, given the passage of time most of the artifacts have suffered heavy degradation.

Bugs

 * The turrets may spontaneously activate when disarming one particular laser tripwire, even if none of them have been tripped. This usually results in the player character's immediate death.
 * After all of the laser trip wires have been disarmed, they can be reactivated by pressing the red button at the end of the hall and disarmed again, yielding an infinite amount of materials. They will only reactivate when the door gets closed, so after the second run, one needs to press the button twice.
 * After the laser trip wire bug(s) it may cause the game to crash and prevent the game from loading at a previous save point. The Player will then have to start the game over from the beginning. Restarting/reloading the game will only freeze at the beginning (load/save area when the game first starts).
 * When hacking into the treasures access terminal, the Protectrons will activate and attack regardless of whether the attempt was successful or not, instead of just the latter.
 * The bugged tripwire will always activate turrets when one tries to disarm it without the prompt 'disarm' displayed on the screen. Pressing the button for 'activate' near any turret also activates the security system. The bugged tripwire can be safely disarmed only with the prompt 'disarm' displayed over it.