I Know This Much is True

After paranoid schizophrenic Thomas Birdsey has a violent public breakdown, Dominick Birdsey finds himself stepping up to defend his identical twin brother in unexpected ways. As he navigates the fallout of Thomas' actions, Dominick reflects on their childhood growing up under the tyrannical rule of their volatile stepfather, Ray, and their persistent desire to know the identity of their biological father. Dominick crosses paths with the prickly Nedra Frank as he attempts to have his grandfather's manuscript translated from Italian into English as a gift for his ailing mother.

Tensions rise between Dominick and his live-in girlfriend, Joy, as the media begins to take an interest in Thomas' case. In his attempt to have Thomas released from the Hatch forensic institute for the criminally insane, Dominick finds a potential ally in social worker Lisa Sheffer, but learns that helping his brother may be more difficult than he thought. Dominick clashes with Thomas' new psychiatrist, Dr. Patel, as she begins to probe into his past. We learn about the shocking tragedy that triggered the dissolution of Dominick's marriage to Dessa.

Sheffer preps Dominick for a pivotal hearing with Hatch's review board that could decide Thomas' fate. A chance encounter with an old classmate brings painful childhood memories to the surface. Dominick reflects on his and Thomas' time together at college, during which he met Dessa and the signs of his brother's illness first began to manifest. Joy attempts to remedy the problems in her and Dominick's relationship.

Despite the protestations of those closest to him, Dominick returns to work before fully recovering from his accident. Heavily medicated, Dominick recalls the disturbing incident that led to Thomas' first hospitalization while counting down the hours to Thomas' hearing with the Hatch review board.

Upon learning the details of his Sicilian grandfather's arrival in the early 1900s to Three Rivers, Dominick becomes convinced his family is cursed – a conclusion that Dr. Patel pushes back against. A startling update on Thomas from an unlikely source prompts Dominick to take drastic action.

A lifetime of animosity between Dominick and Ray spills over in public at an inopportune time. After an unexpected tragedy, Dominick seeks reconciliation with those he has hurt. The question that has plagued Dominick all his life is finally answered.