An unlikely witness threatens to expose the perpetrators of the woods massacre. As Nucky re-evaluates his relationship with Lucy, Margaret starts a new job. Chalky's team pays a heavy price for taking over Mickey Doyle's bootleg operation, causing Chalky to reevaluate his relationship with Nucky. After questioning Angela's loyalty, Jimmy heads west.

Nucky's attempts to usher in a joyous St. Patrick's Day are undermined by Eli, Margaret & Van Alden. In New York, Arnold Rothstein worries about his involvement in the fixed World Series, while in Chicago, Jimmy copes with the aftermath of a vicious attack orchestrated by Torrio rival Charlie Sheridan.