A new biopic is rounding out its cast with a different sort of mad man. According to Variety, Mad Men star Jon Hamm has joined the cast of the biopic Howl.

Hamm rounds out the cast that already includes James Franco, Mary-Louise Parker, David Strathairn, Jeff Daniels, Bob Balaban, Treat Williams and Alessandro Nivola. Hamm will portray defense attorney Jake Ehrlich, who was also the inspiration for the hit TV series, Perry Mason.

The film, which revolves around the obscenity trial of notable poet Allen Ginsberg, is currently shooting in New York City.

Howl was released September 24th, 2010 and stars Jon Hamm, James Franco, Mary-Louise Parker, Jeff Daniels, David Strathairn, Alessandro Nivola, Treat Williams, Aaron Tveit. The film is directed by Rob Epstein, Jeffrey Friedman.