Grey’s Anatomy alum T.R. Knight is returning to ABC to costar in the Reese Witherspoon divorce drama pilot, EW has learned.

The untitled project from Meaghan Oppenheimer follows a ruthless Dallas divorce attorney, whose life begins to unravel when her emotionally damaged, love-addicted sister resurfaces, triggering self-destructive tendencies and exposing long-hidden family secrets.

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The Emmy-nominated Knight, whose credits also include 11.22.63 and The Good Wife, will play Mark, an associate lawyer at the firm aiming to become partner.

Oppenheimer will write and co-executive-produce alongside Witherspoon and Bruna Papandrea. Jeremy Podeswa will helm the pilot.