As Flack cleans up his wounds, he tells Terrence he should get new friends. He realizes that Mac is there. Terrence says he would appreciate if they leave using the back door. Mac angrily tells Flack he can't believe he went AWOL during a murder investigation. Flack says something has been eating at him. He explains after Angel was killed, all he wanted to do was make things right. Mac tells Flack he is not his priest, but needs to know if he can count on him.

Stella and Danny go to the hospital and show the director a sketch of the compass killer. She says the man might be Hollis Eckheart. She says Hollis suffered from PTSD. She explains Hollis disappeared a few years ago. She says they give their patients dignity and freedom. She says they kept Hollis's room intact. Stella and Danny examine Hollis's room and discover pictures of the previous victims. They see a picture of a woman named Calliope. Stella figures Calliope was the person's initials who was engraved in one of the compasses. After Danny suggests they speak to Calliope, Stella informs him that she died two years ago.

Flack returns to the station. He apologizes to Mac. He explains he was pretty messed up the last couple months. He states he appreciates his patience and support. Mac explains everyone mourns differently, but thinks there is something else. He asks if he dealt with his issues. Flack says he knows he crossed the line, but it won't happen again.

Mac confirms that Hollis's DNA matches the killer. Flack says he worked Calliope's murder case. He plays an audio tape which shows Calliope as a victim of a spree shooting. He explains while Hollis visited his wife at her work for his birthday, an angry boyfriend of a coworker started shooting. The man went door to door and massacred the workers. Hollis held the door to his wife's office, but was shot in the face. The man found Calliope under the desk and shot her to death. Mac figures that even though Hollis was in deep pain, it is no excuse to seek revenge.

The team discovers a vehicle they suspect was used to move Richard. They find blood splatter in the trunk. Danny finds rope shavings and figured Richard cut his way free. They figure Richard fought back, but was shot. Stella reports that Adam found Terazzo on Hollis's shoes and substances on the rope that could be found at a water treatment facility in Queens. After examining Hollis's drawings, they figure that Hollis is heading to a fair held at Flushing Meadows. At the park, Mac notices a man siphoning gas. Hollis runs after he realizes he has been spotted. Helicopters hover over as they chase Hollis through the park. After minutes of searching, they realize they lost Hollis.