Shiloh Nelson

The BAU investigates a double homicide and kidnapping in New Hampshire. Also, Rossi's plans to elevate his relationship with Krystall (Gail O'Grady) don't go as planned.

Walden reconnects with Kate and is sure she's "The One" – that is, until he meets Vivian (guest star MILA KUNIS – That '70s Show, Black Swan), a beautiful, free-spirited world traveler who shows up on his doorstep. Feeling an instant connection with Vivian, he soon becomes convinced that she's "The One." Meanwhile, Alan and Gretchen grow closer.

A former U.S. Border Patrol tactical officer disappears following a threat by the cartel.

With Christmas celebrations in full swing, Will (David Walton) is in agony over the cheerfulness around his least favorite holiday and the constant playing of his hit song “Runaway Sleigh.” With his lawsuit still pending, Laurie (Annie Mumolo) advises Will to settle and move on. Refusing to give up any of his earnings, Will and Marcus (Benjamin Stockham) go on a search for the original handwritten song lyrics as evidence to prove he is the sole writer of the song. Meanwhile, Fiona (Minnie Driver) and Andy (Al Madrigal) try to create the perfect white Christmas for Marcus.

Avery welcomes D.B. Russell to the team as they investigate a burglary/homicide committed by someone who hacked the home's security system remotely. Also, Avery considers moving to a new position within the hierarchy of the FBI, Krumitz is a witness in his sister's trial, Elijah deals with a delicate family situation and more is revealed about Nelson's and Raven's backgrounds. Ted Danson joins the cast as D.B. Russell, the new Director of Next Generation Forensics, who transfers to Washington, D.C. from Las Vegas.