A man is shot and killed during a party on his yacht. As a second victim is about to be shot, a body drops from the 59th Street Bridge onto the yacht, catching the shooter by surprise and saving the second man from certain death. The jumper initially looks like a suicide until Sid finds that he was shot and the suicide jump was staged. When Hawkes dives into the East River to search for the gun that Stella believes the killer threw over the bridge along with the body, he doesn't find a gun, but a compass instead -- the Compass Killer has struck again -- claiming a third victim. The team gets a break when fibers found on the third victim lead to a state-of-the-art psychiatric hospital. The facility administrator recognizes the composite sketch of the Compass Killer giving Stella the name she has been waiting for -- Hollis Eckhart. Eckhart was a patient at the facility after his wife was murdered during a workplace shooting rampage two years prior. Flack knows that the victims have some link to the shooting spree which is why Eckhart targeted them. The evidence trail leads them to the World's Fair where they find Eckhart. A chase ensues with a huge show of force but Eckhart again disappears. Mac is more determined than ever to find Eckhart and stop his killing spree.