Doc Roy and his dog Buster are hanging out at the Ground and Hound dog cafe when a wounded woman, Louie Hall, in a bomb vest arrives. She's pursued by police.

She was involved in a bank robbery in which a cop had been shot dead.

Heading up the scene is Cath Welsh, who has history with J.D.

She agrees to let J.D. negotiate with Louie, based on his experience.

Blue hacks the woman's phone then the closed-circuit feed. Louie gets a call but the caller is gone by the time Evie and DeShawn reach the phone booth.

J.D. starts negotiating with Louie. She demands a chopper, painkillers, and a talk with the health minister.

Mackey talks with Louie's mother while D chats with her sick younger sister, Casey. Casey heard Louie talking with a man called Stone on the phone.

Doc attempts to treat Louie's gunshot wound.

J.D. brings Louie her painkillers. A man runs when she asks him to get the pills.

Casey suffers from an aggressive form of leukemia.

Louie's accomplice is Stone Matthews. The team goes to pick him up but he's not home.

Roy tells Louie he just put his wife Alice, who has dementia, into a facility. She calls him at the cafe. He and Louie bond over their sick relatives.

Louie is using disappearing texts and Blue can't retrieve them.

The police sends a bomb-sniffing dog into the cafe. Louie thinks the explosives on her vest is fake but the dog reveals it's real.

Surveillance proves Stone, not Louie, shot the cop. 

Stone reveals the explosives are real. He grabs Casey for leverage.

J.D. tries to convince Cath not to shoot Louie. He wants her to jam the signals.

Stone is Louie's mother Fiona's drug dealer. She sewed the bomb vest.

Louie is robbing the bank to afford experimental drugs for Casey.

Fiona tries to convince her to surrender. 

Stone says he'll trade Casey for the money Louie has hidden.

Police HQ refuses to jam the signal as J.D. had hoped.

Blue freaks out and Mackey has to talk her down.

Blue figures out how to track Stone and the others go after him.

J.D. and Cath jam the signals anyway.

They rescue Casey and Mackey shoots Stone.

The timer on Louie's vest starts counting down when she tries to take it off.

Roy stays wih her pretending to be the health minister so she could tell him off to distract her.

The bomb tech disconnects the bomb.

Blue takes Roy to visit Alice.