Psych 1. Sezon 9. Bölüm (Forget Me Not)

Henry's old captain believes he's solved a murder, but his Alzheimer's has caused him to forget the most important details: the crime, and who committed it.

Henry calls in Shawn and Gus who find themselves investigating a murder that happened decades ago and only the faulty memory of the retired officer gives them any hope of closing the case.