Caplan is one of three actors who signed on for Cusack's "Hot Tub Time Machine," according to The Hollywood Reporter. She'll be joined by Crispin Glover (as a wacky -- and knowing Glover, definitely creepy -- bellhop) and Sebastian Stan (as a cocky ski instructor).
The plot follows four buddies who, missing their wild high-school days, stumble upon the titular device and revisit 1987. Rob Corddry signed on in February.
Glover, 45, stars in this year's sci-fi flick "9." Caplan, 26, co-starred in 2008's "Cloverfield." Stan, 25, co-starred on the NBC series "Kings."