Brit thesp Tiffany Mulheron (“RocknRolla”) has joined the cast of Jules Stewart’s directorial debut “K-11.”

Goran Visnjic (“ER”) stars as a successful record producer who wakes up after a three-day drug binge in a special unit of L.A. County’s Men’s Central Jail dedicated to vulnerable prisoners.

Mulheron will play Visnjic’s trophy wife who, fed up with his chronic drug use, starts seeing one of his pop star clients behind his back.

Portia Doubleday co-stars in a role once ear-marked for the helmer’s daughter, “Twilight” star Kristen Stewart, whose older brother, Cameron Stewart, will make his feature debut in the indie pic. Cast also includes D.B. Sweeney, Jason Mewes, Tommy “Tiny” Lister, Billy Morrison, Clarie Sinclair, Tara Buck and Kate del Castillo, who plays a transsexual who rules the prison unit.

Jules Stewart and Jared Kurt co-wrote “K-11,” which is being produced by Libertine Films prexy Tom Wright Jr. and exec produced by Michele Berk of Lotus Pictures. Intandem is repping international sales for the pic.

Mulheron, who starred on the CW’s “Life Is Wild” and appeared on the J.J. Abrams-produced NBC series “Undercovers,” recently wrapped Brian Brightly’s indie thriller “Liars All.”

Mulheron is repped by Thruline Entertainment, Troika and Abrams Artist Agency.