Writer/creator Jonathan Ames has revealed the Porcelain hitmaker will play the boyfriend of Stewart's ex-wife.
Ames tells WENN, "She's gone for another bald man."
And there will be other cameos for the director's pal Jason Schwartzman, and Stewart's real-life son Daniel, who will play his son on TV.
Ames adds, "He plays a boxer. We kind of have a boxing, a little bit Raging Bull, Pulp Fiction nod in that particular episode."
Blunt Talk debuts in America on Saturday (22Aug15).