Mysterious serum

Mysterious Serum is a consumable item in Fallout 4.

Characteristics
A unique consumable obtainable only through the quest lines of Special Delivery and The Secret of Cabot House.

Eleven can be obtained during these quest lines, twelve if the player can pass a speech check convincing Jack Cabot that no serum was found, or thirteen if the player sides with Lorenzo Cabot to the very end of the The Secret of Cabot House. Should the player decide to free Lorenzo, they get access to an infinite supply of this item, with a few caveats: one may receive only one at a time and only when the Sole Survivor has none left, and you may not sell or store the serum in any way.

The item's description lists a Radiation effect of -36000, but this is misleading; it does not act like a RadAway. Rather, this number comes from removing 10 rads per second for 3600 seconds (60 minutes or one hour).

One potential use case is for boosting carrying capacity while scavenging. The boost of +5 STR is significant, as the similar consumable Buffout gives just +2, and any chem mixed with it +3.

Another use is most helpful when the perk Ghoulish is acquired and fully upgraded. When standing in irradiated water without Radiation resistance, the player will effectively take no new rads, but can gain up to 15 Hit Points per second.

Locations

 * One at Parsons Creamery.
 * Three on Raiders in Parsons State Insane Asylum.
 * Three on a tray in Lorenzo Cabot's chamber within Parsons State Insane Asylum.
 * Five on a named Raider, Lefty, who is stationed in Lorenzo's chamber.
 * One given by Lorenzo if the player sides with him to the end of The Secret of Cabot House. This can be renewed if the player has none left in their inventory. See details in the Characteristics section above.