It's a full moon which always makes things interesting when you're a police officer. Protect, serve and be on the lookout for werewolves.
Andy finds a diamond engagement ring amongst Luke's things. She wasn't snooping. Honest! Luke hadn't planned to pop the question this way, but he's fine with the end result as Andy happily tries on her brand new bling. We get the feeling that Sam's congratulatory handshake at roll call wasn't one of genuine happiness.
Sam and Andy make a gruesome discovery at the scene of a car crash. Three severed heads are found in the trunk of a car. The driver took off, but not before Andy and Sam got a good look at him. The car with the heads belongs to a woman named Tanya, who had no idea it had been stolen. Andy gives the woman her card should she think of anyone who matches the suspect's description.
The severed heads were swiped from the hospital morgue. Andy has a scuffle with the suspect in a secured room. The guy actually bites her on the hand before escaping once again. There's been a full moon, so hopefully the guy's not a werewolf.
As it turns out, the suspect is a hospital researcher named Daniel Baird. He's a schizophrenic who recently went off his meds. Daniel even blames the police for interfering with the fictional relationship with Tania he built up in his mind. He even threatened to track Andy down to stop her lies about him.
Dov has been looking to prove himself ever since he got busted down. None of the training officers want to ride with this enthusiastic young officer. That's fine. Gail volunteers to be his supervising officer. It's a prime way to pay him back for all the roommate grief he's been giving her. Oliver just wants Gail to keep him out of trouble. Easier said than down, right?
A concerned mother wants Chris and Traci to believe that her daughter is the shooter in the murder of a crack dealer. She's not. It's just a desperate move by a mom who lost her child to the streets. The case was low priority, but Traci makes sure it has new life. Jerry appreciates how the situation exemplifies her "family first" mindset. That's why he won't push Traci to move away from Leo's dad even though she's sleeping with him.
As we all know, Luke's had a past relationship with Detective Jo Rosati. What we didn't know is that he once proposed to her using the very ring Andy now where's on her finger. Luke catches some grief from Jo about this issue, but reminds her that she's the one who said no. He heads home unaware that Daniel Baird is there, too. The mentally disturbed man holds Luke's gun in his hand. BANG! BANG! Luke is shot twice in the stomach.
Gail and Dov respond to a noise complaint. They have no idea that it's near where Andy and Luke live. Dov catches sight of Daniel Baird wandering in the street. There's something off about the guy. Gail runs his info. When they realize who he is, Daniel puts a gun to his head. Dov is able to tackle him before he can pull the trigger. Later, Gail is so impressed by Dov's instincts that she actually hugs him.
When Andy arrives at the scene, she recognizes Luke's firearm. She takes off to the house where Luke is bleeding out on the floor. He's alive, albeit barely. The next 48 hours are critical. Andy wants to see him, but ICU is restricted. Family only. That's fine. She's his fiancee.
Andy is allowed to set by Luke's hospital bed while his other brothers and sisters in blue wait outside. Both Sam and Jo are among those concerned colleagues hoping Detective Luke Callahan pulls through.