Criminal Minds TVGuide Scoop SPOILER!

Criminal Minds' Thomas Gibson teased the November 10 episode, guest starring Prison Break's Robert Knepper. "Rob plays the son of a movie actress from the '50s, and the poor kid is pretty twisted," he says. "He kidnaps these girls and dresses them up like '50s movie stars and then kills them. It's fantastic!" Gibson also talked about the arrival of guest star Rachel Nichols, who plays an FBI cadet starting in late November. "I don't want to give too much away, but she has a particular perspective that the team will find invaluable in a specific case." Though Gibson's stingy with the details, he will say that Nichols was not hired to replace former Minds' cast member A.J. Cook. "I don't think that anybody is intending for anyone to be her replacement. There's no replacing the character, and there's no replacing the actress," he says. "I think one of the things that we did in some of the subsequent episodes of her leaving was to play that it was hard to fill her shoes."