That Sinking Feeling

 is a quest in Fallout 76. It was introduced in Patch 8 in April as part of Wild Appalachia series of content.

Synopsis
After reading a "Cryptid Hunter Monthly" issue on the Sheepsquatch, the dwellers discover that someone named Scoot Conroy had left a handwritten message at the bottom. He claims to know the "truth" about the Sheepsquatch. They can search his shack for clues to learn more.

Walkthrough

 * The quest is started by picking up C.H. Monthly, January, located at the following locations:
 * Lewisburg:
 * Point Pleasant
 * Ranger District Office:
 * Southern Belle Motel: On a shaded table close to Boomer
 * Valley Galleria:
 * Once these are located, it's time to find Scoot's shack. It's located to the south of the Southern Belle Motel on a ridge, and to advance, the player needs to gain access to his research computer. The "Research" section of Scoot's computer requires a special passphrase. The bits and pieces are found around his shack and in other parts of the terminal. The phrase is 4 letters plus 4 numbers.
 * Letter to L is the cipher to the password.
 * Birthday Present Ideas entry on Scoot's terminal.
 * Cats were very important to him, and he mentions a list of birthday present ideas on the terminal. The passphrase is the name of his cat Mari and her birthday. Scoot's truth about the sheepsquatch is less than enlightening, so it's time to track down the man himself. Scoot left behind research notes on a sunken church in the Mire and it seems this was the last place he went before he disappeared. The sunken church is located right behind Raleigh Clay's Bunker and Scott is found inside. He has also left several notes, Day 1 and Day 82, that can read along the way that gives the history to his predicament.
 * The sad truth is that he lost his mind after he was force-fed human flesh by another survivor. Scoot would eventually kill the other survivor, but would still continue eating human flesh. Reading his final note, A New Day, will trigger an attack by a strange creature...