Topher Grace has boarded Lionsgate‘s action comedy American Ultra, adding to a cast that already includes Jessie Eisenberg, Kristen Stewart, Uma Thurman and Walton Goggins. This is the pic Lionsgate scooped up just after Berlin with a $7M pre-buy for U.S. distribution rights, one of the richest deals to come out of the fest this year. Directed by Nima Nourizadeh (Project X) and a script by Chronicle scribe Max Landis, Ultra centers on Eisenberg’s character, a stoner whose small-town life with his live-in girlfriend (Stewart) is upended when his past catches up with him, putting him the crosshairs of a government operation bent on wiping him out. Grace will play a hotshot CIA agent who has recently taken on seniority that has gone to his head, and power-hungry he begin a mission to kill a secret government asset. Grace, repped by ICM Partners, Brillstein Entertainment and Ziffren Brittenham, recently wrapped production on Christopher Nolan’s Interstellar and is shooting Home opposite Patricia Clarkson.