They finally start to piece together clues, knowing that there are some people out there going to die soon by this mysterious serial killer. Thinking they've seen it all somewhere else before, Amelia heads off to a creepy library, with creepier librarian, and luckily finds a paperback of 'The Bone Collector' with nice pictures of the elaborate murder scenes in the story to save her reading the words.
She immediately calls it in, and the Coast Guard and NYPD turn out in force at the docks. After talking on the radio to Lincoln, she decides to check out the end of the pier - and finds two bodies tied to a post, about to be submerged by the water, and dives in to rescue them. She signals the cops and they drag the bodies out the water - the old man dies but they revive the young girl.
Now that her heavy woollen sweater has fully dried out after a minute or so out the water, she hunts around for clues - and finds an old subway map, a bone, and a piece of broken metal with "PD" on it. She hides the evidence, calls it in to Lincoln, and ducks away before the meddling captain can get in on it.
Lincoln calls up on the maps on his super beside computer, and Amelia is sent to a disused station - and of course loses radio contact. Full of dust, the only clue is a number on the side of an old carriage that has been cleaned. She runs through her memory of every number she's ever seen - and finally stops at the number on Lincoln's wall - his old PD badge number.
Meanwhile, Thelma goes to answer the door and is dispatched fairly quickly - but with a bit of blood that needs to be tidied up. The killer lets himself in and cleans up. We soon see that it's the forensics, nerdy guy - Richard Thompson.
Lincoln tries to set off the alarm, but the murderer disconnects his power and life support system. He monologues about being a brilliant forensics guy, until he tampered with evidence to bring down some bad guy - and Lincoln ratted on him. In jail he was 'brutalised' every day, and planned his revenge.
As he feels around the metal bed for something, Lincoln releases a lever and crushes the bad guy's hand. They kind-of get into a bit of a fight, until the murderer finds a knife is about to kill him ... until Amelia enters the room just in time and shoots a few slugs into his chest.
Now that it's all over and he wants to live again, Lincoln has a birthday party and Amelia invites around her partner's family - and it seems they both have feelings for each other now which is nice. Just a shame no one thinks about the poor home helpers.