Mekhi Pfeiffer, Cheech Marin

Mekhi Phifer and Cheech Marin will guest-star in an episode of Psych, TVGuide.com has learned exclusively.

Phifer, who stars as a not-so-dead dead man on Torchwood: Miracle Day, will play Drake, a member of "Blackapella," the a cappella group Gus (Dulé Hill) belonged to in college. Drake comes to town to honor Deacon Jones (Up in Smoke's Marin), his mentor from childhood. But the deacon is shot while receiving the honor at the local community center, and the group steps in to help Shawn (James Roday) and Gus investigate.

USA sets premieres for Burn Notice, Psych and Covert Affairs

Jaleel White and Kristy Swanson will reprise their roles as Tony and Marlowe, respectively, in the episode. Liza Lapira, who's set to guest-star in ABC's midseason comedy Apartment 23, also will appear.

Psych returns for its sixth season on Wednesday, Oct. 12 at 10/9c on USA.