Jess invites Paul (guest star Justin Long), a music teacher at her school on whom she always has had a crush, to the gang’s big Thanksgiving dinner at the loft, which naturally goes horribly awry.
Two young engaged scientists die in a fire and a mentally challenged neighbor Charlie Headlind (Guest Star Christian Anderson) is badly burned trying to save the couple. Detectives Cyrus Lupo (Jeremy Sisto) and Kevin Bernard (Anthony Anderson) discover that both of the victims were stabbed before they burned in the fire, leading them to a mentally disturbed woman, Wendy Teal (Guest Star Gretchen Hall), Charlie's former girl. Also stars S. Epatha Merkerson, Sam Waterston, Linus Roache and Alana de la Garza.
Cheryl and Dana are forced to smash their way out of a locked garage because they ignored Jim's lesson on how to open the door from the inside.
Secret agent James T. West poses as a notorious desperado, Frank Slade, inaplan to arrest a Mexican bandit, Colonel Vasquez, who has been robbing banks in American border towns and then fleeing to the sanctuary of Mexico.
Sam goes undercover and infiltrates an Irish gang to take down their ringleader who has killed multiple people; Sam learns more about himself while undercover and is worried he is more like his violent father than he thought; Sam finds himself attracted to the gang leader's sister.
