On Election Day in New York City, another killing hits close to home for the detectives of the Sixth Precinct on this episode of Copper. They discover Mary Lockwood's body in Central Park. Maguire seems convinced that McLean did it, and in a chase guns the man down before they can interrogate him. Forensic evidence makes Corcoran suspicious of Maguire and he has him tailed.
Corcoran's investigation of Maguire leads him to an insane asylum where he's introduced to "Mrs. Maguire". However, it's actually Corcoran's wife and Maguire has known she's been there all along.
Morehouse is still involved with the Southern rebels, but foils their plan to blow up NYC after Lincoln wins the election.