"Trending Down" will star Hoffman (Death of a Salesman, Long Day's Journey Into Night) as a man whose life begins to crumble when his advertising agency is taken over. It is characterized as a "blistering attack on our youth-obsessed culture, and a darkly comic examination of what it means to matter. Or matter not."
Hoffman will play Thom Payne, with Kathryn Hahn expected to portray his wife.
Mitchell, who also directed his film of Hedwig, has directed "Short Bus" and "Rabbit Hole."
Shalom Auslander ("This American Life") created the series that was developed by Ken Kwapis.
Holed up in a seedy motel on the edge of the Mojave Desert, two former lovers unpack the deep secrets and dark desires of their tangled relationship, passionately tearing each other apart. Led by director Daniel Aukin (Back Back Back at MTC, 4,000 Miles), Tony winner Nina Arianda (Venus in Fur at MTC, Born Yesterday) and Sam Rockwell (A Behanding in Spokane, The Way Way Back) bring an explosive intensity to Sam Shepard’s (Buried Child, True West) landmark myth of the new Wild West.