The episode opens a month ago when Stuart was feverishly trying to crack a tattoo. We find out that Hirst went to see him at his apartment and slit his throat with her own hand.
Back in the present, Allison has brought baby Bethany to see Kurt and Jane for an early Christmas.
Weller has a nightmare about Roman and Berlin. He and Jane worry about Patterson and the rest of the team working on Hirst's case all day and night in their apartment.
Zapata and Reade hash out their differences, Z gives R some advice about the gift he got for his girlfriend.
Roman sends Bethany a Christmas present -- it's a clue for the tattoo that Stuart was working on. The Van Gogh painting.
The tattoos points to a clinical trial to treat cancer patients. Employees working on the trial have wound up dead. The team decides to go to the hospital undercover.
Jane and Kurt meet with the director of the Clinical Trial - Dr. Palmeri. They ask about Nurse Emily Brown who committed suicide. Palmeri gets defensive.
Jane and Kurt find another black box under a Christmas tree at the hospital -- another clue from Roman. It's schematics of the hospital pointing to the server room.
Reade and Zapata go to the server room and Zapata copies data off of the servers. Z asks R why he had met with West and Reade says he was helping someone out of a tough spot.
Hirst calls Reade - she wants to have breakfast with him. Reade says he has plans with Zapata, she invites her too, wanting to "get to know the team more."
The data from the server shows that Dr. Palmeri was deciding which patients were going to get the placebo and which were going to get the drug. She was accepting bribes from families because she's in debt.
Jane and Weller were meeting with one of the patients in the trial. His husband comes in and turns out to be the one-eared guy.
Jane and Weller bring "Van Gogh" to their apartment, tied up. He counters them, asking for a lawyer and why this is all so "unofficial." They've discovered his real identity is Eric Vance.
The team needs to get Eric on their side in order to take Hirst down in a way that will hold up in court -- they bring Allison in to help, although she's less than thrilled.
Two years ago when she was working as a prosecutor on a high-profile case, Hirst was put under protection and Vance was the Marshall assigned as her security detail.
Reade and Zapata talk to the husband Julien, who has no idea what Vance has been doing.
Hirst was responsible for making sure Julien received the life saving treatment from the trial and uses that to blackmail Vance into working as a "fixer" for her.
Hirst has some sort of leverage on Dr. Palmeri that is allowing her to control what happens with the trial. Jane and Weller want to remove Dr. P in order to protect Julien and then Vance will testify against Hirst.
Weller goes to see Palmeri, but she has already left for her meeting with Park -- her research assistant from her pharmaceutical company. They are planning to release a virus that they've created an antidote for so they can become rich and powerful.
Allison, Jane, and Weller go to the lab to get Palmeri -- they are gone, but there is a lab full of dead lab rats and a missing virus.
At brunch Hirst demands that Reade revoke Zapata's FBI clearance and remove her from the team because "she can't be trusted."
The team goes to a Manhattan water treatment plant and find Park -- she has released infected rats into the pipes.
Kurt goes after Palmeri while Jane and Allison work together with Patterson's help to shut down the water plant and protect the virus from getting out.
Vance reveals to the entire team what he did for Hirst, including digging up dirt on the other candidates up for her promotion, finding an Assistant Director that would be easy to manipulate (Reade), and staging Stuart's murder to look like a suicide.
Weller defends Vance's actions because he was just protecting the person he loves, Allison says that's not fair and dishonest is just dishonest.