Special Delivery

Special Delivery is a side quest in Fallout 4.

Detailed walkthrough
Upon visiting Bunker Hill, Edward Deegan will approach and offer work. If you previously visited Parsons State Insane Asylum and killed a few of the guards, he will mention it and act like you need to "make up" for it. After accepting go to the Cabot House and use the intercom to gain entry, then speak with Jack Cabot and Edward Deegan about the job. A package has gone missing near the insane asylum that's owned by the Cabot family.

Head up to the asylum and question the guard captain, she'll mention that the raiders that stole the serum are at the Parsons Creamery to the north. Head up there and confront them, if you wait on arrival then a fight will break out between them and they'll thin their numbers.

Kill the remainder, take the serum, return to Cabot House. There is an option to lie to Edward Deegan with an easy persuasion check to keep the serum at the cost of a few caps of reward, or it can be turned over. The quest ends either way, automatically starting the quest Emogene Takes a Lover.

Bugs

 * Edward and Jack may attack you as soon as you enter Cabot house. Defeating them does not solve the problem as they attack again once their life is restored. This is usually because you've attacked their Sentry droids outside. This can be fixed by taking some time away and coming back at another time.
 * You may not be able to interact with the beginning intercom while in power armor. Leaving the armor allows you to use it.
 * Mercenaries may attack you when you show up to the asylum. Defeating Maria does not solve the problem as she attacks again once her life is restored. To fix this do the command "setstage 503b8 35". The player can also approach the asylum in stealth mode and once the location is discovered the mercenaries will be reset and not attack.
 * Could be caused by target matrix and/or Tesla coils attachments for power armor. Removing them seems to work.
 * When deathclaws appear in Lynn Woods they may wander off to Parsons Creamery and kill raiders inside. This renders corpses unlootable.
 * You may not be able to activate the "Special Delivery" quest. Sometimes Edward Deegan will not spawn anywhere other than Cabot House and once you enter and try to interact, there is no dialog, only automated responses, and he will not give you the quest. You may have to restart from an earlier save, or try some other method of activating the quest.
 * Edward Deegan will not spawn in Bunker Hill as long as the "Battle of Bunker Hill" quest is active. After completing the quest he does spawn there immediately.