Jimmi Simpson (Westworld), who played Mary Lightly on USA dramedy series Psych, will return to reprise his role in Psych: The Movie, which is set to air in December.

Simpson made the announcement today during the Psych reunion panel he moderated at San Diego Comic-Con, featuring series stars James Roday, Dulé Hill, Maggie Lawson, Kirsten Nelson and Corbin Bernson; creator Steve Franks; and executive producers Chris Henze and Kelly Kulchak.

Psych: The Movie, from Universal Cable Productions in association with Tagline, hails from Psych creator Steve Frank and will feature the series’ core cast led by James Roday and Dulé Hill. It picks up three years after the series finale as the gang reunites after a mystery assailant targets one of their own. Psych aired from 2006-14 on USA.

Previously announced guest stars include Zachary Levi (as Thin White Duke), Jazmyn Simon (as Selene), Ralph Macchio (as Nick Conforth) and WWE Superstar Charlotte Flair (as Heather Rockrear).

USA also released a promo featuring Shawn Spencer and Gus Burton getting back in shape for the movie. Watch below: