Juan Carlos Cantu

Dexter hires a nanny; Debra is annoyed with her new partner; Quinn continues to investigate Rita's murder.

Gideon, Hotchner and their team head to Mexico to aid in the investigation of a serial killer who preys on the elderly.

Ruth and Bettina take a trip to Mexico; Claire warms up to Jimmy; Nate is indecisive about his relationship with Brenda.

Special Guest Star Michael J. Fox. -- Elliot finds herself perplexed over a simple procedure that leaves her questioning her career path. She goes to seek Dr. Kevin Casey's (guest star Michael J. Fox) advice but becomes frustrated when she learns that the epiphany toilet, which the Janitor secretly installed on the roof, is getting more attention than she is. Meanwhile, Turk asks J.D. to be his best man at his wedding, which sends J.D. momentarily into sheer bliss, until he hears a phone message that makes him question his friendship with Turk.

Richard must make a difficult decision.

Don't die.