Misty, a superstar singer deciding to retire, receives a terrifying fan letter. Her head of security hires McCall to track down the culprit.

Dr. Manning and Dr. Rhodes separately treat complicated cases involving sick babies, only to uncover that the two cases could actually be intertwined. Elsewhere, Dr. Halstead and Dr. Charles treat a homeless man with an upbeat disposition who sheds some valuable insight that prompts one of the doctors to learn a thing or two along the way. Dr. Choi has a Navy corpsman follow him for the day as they deal with the toll of gang violence in the city, while Dr. Reese tries to understand the delicate balance required in her new position.

September 13, 1956: After Tom Stratton comforts his wife and prevents her from having a premature birth, instead of leaping to save his wife and child. He instead realizes that instead of leaping home, he's lept into Ken Fox, a minor league baseball player in Texas at the end of the 1968 season, in the middle of a game, where he must make the winning play in order to leap further. Ken Fox makes a home-run, and Sam leaps into Dr. Gerald Bryant as a school teacher in the middle of a class.

September 13, 1956: Sam Beckett wakes up in 1956, disoriented, suffering from amnesia, but he has the awful realization that he does not belong there...

The Santa Ana winds bring in a variety of weirder-than-usual emergencies as the 118 respond to a family dog retrieving a severed hand and a young woman sleep-driving into the station. Bobby worries about his AA sponsor. Denny questions Hen and Karen about his biological parents. Chimney thinks he's found the perfect house for him and Maddie.

When a lack of evidence leads Barba to drop rape charges against a popular actor; Rollins takes matters into her own hands.

One of Scully's friends from the FBI academy, now working in the Violent Crimes Unit, asks her to assist him on a homicide investigation involving no clear point of entry. Mulder realizes that this is similar to a series of X-Files cases that have occurred every thirty years and joins in the investigation to stop the latest cycle.