No question about it: Greg Grunberg is joining ABC’s pilot Doubt, TVLine has learned.

The legal drama from House creator David Shore centers around Vincent, a former cop-turned-charmingly low-rent lawyer who uses his street smarts and cunning to work the system for his clients while battling his own demons and wooing his ex-wife.

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Grunberg — whose credits include Heroes, Alias, Felicity, and, more recently, Lifetime’s The Client List — will play Vince’s developmentally disabled by high-functioning older brother Mark. He works at Vince’s office as the receptionist and believes that his brother can save the world.

Sons of Anarchy‘s Rockmond Dunbar co-stars as Vincent’s former partner on the force and current confidante.