'NCIS: LA' books Michelle Trachtenberg for action-packed episode

Michelle Trachtenberg is visiting the gang at NCIS: LA.

EW has learned that the Gossip Girl alum, who recently appeared in Killing Kennedy, will guest star in an action-packed holiday episode set to air Dec. 17 on CBS. She will play a character named Lily, a smart and witty environmentalist/ private chef who is the victim of a home invasion that "turns her life upside down," according to a casting description.

"We're very excited to have Michelle guest on the show," said exec producer Shane Brennan in a statement. "It's a very intense episode which pairs Michelle with Callen and Sam, in what is probably one of our biggest action shows so far this season." Which is saying a lot.

NCIS: LA continues to perform solidly on its Tuesday night time slot following mothership NCIS. It's most recent episode scored more than 14 million total viewers and a 2.4 rating in the coveted 18-49 demo.