Danny and Gormley race to find Gus Vanderlip, a committed detective who is dangerously determined to uncover how a rapist he arrested is back on the streets; on the eve of their anniversary, Jamie and Eddie are sent on an undercover assignment to expose a corrupt sober living house; and Henry asks Frank for a favor regarding the NYPD's 9/11 Victims Compensation Fund.

Danny joins forces with British investigator Christopher Granger to pursue a deadly international fugitive, and Erin faces pressure from her boss, D.A. Crawford, to secure an indictment against an officer. Also, Jamie investigates a sports gambling website accused of scamming its users, and Frank clashes with Mayor Chase when the mayor uses his authority to have a retired cop released from jail.