When Lt. Ruiz reports a Peeping Tom, Dan theorizes that she was followed home by someone in her yoga class, so he goes to the class and hands out "safety whistles."
Meanwhile, three men meet in a conference room. Wallace says that computer tech Theo discovered a buried Blackbird safety report that reveals Drayton Oil knowingly profited from unsafe and illegal drilling practices. If they go to the Feds, Drayton will be shut down - and they'll lose their jobs. Ashford suggests selling this info to a competitor for a couple million dollars each. Sounds good to everyone.
As new forensic tech Samantha briefs Jack on sex offenders in Ruiz's neighborhood, Asst. D.A. Liz Traynor asks Jack to join her and her new boyfriend for dinner. Jack declines.
While patrolling Ruiz's neighborhood, Dan sees a blonde woman shoot a man named Theo and escape in a car. As Dan and Jack investigate the crime scene, Theo's phone rings. Dan answers. The caller -Wallace - voices second thoughts about their plan. Then he realizes that Dan's voice isn't Theo's and hangs up.
Frightened, Wallace calls Ashford, who tells him lay low; he'll sell the file in two days. Ashford then visits Liz - who greets him as Kyle (!) - and invites her to accompany him to a tropical island two days from now.
As Ruiz discovers that Dan has moved his trailer to her front yard, Samantha tells Jack that she traced Theo's phone call to Scott Wallace. Wallace, meanwhile, is currently out cold, with that blonde woman scattering pills on his sheets. She's interrupted by a call from a man who says he paid for a corporate cleaning, not a giant mess. She replies that the witnessing of Theo's murder was a fluke and it's under control.
Then Jack and Dan burst in. Wallace regains consciousness, moans "Drayton oil" and "Blackbird," then passes out. As Jack and Dan try to revive him, the blonde hides under the bed.
Back at the station, Jack discovers that "Blackbird" refers to a five-year-old safety report in which Drayton Oil came up completely clean. Ruiz warns that owner Patrick Drayton is rich and powerful, but Jack says that he's got an inside source: Kyle Ashford.
Once Ashford learns that Theo's been murdered and Wallace tried to commit suicide, he tells his secretary to cancel everything, but Jack and Dan are waiting in the lobby. When they question Ashford, he's nervous. They want to see Patrick Drayton. Ashford tells them to wait in his office - and runs.
Meanwhile, Drayton is on a golf course, telling the hitwoman that he suspects Hewitt Petroleum CEO Marshal Hewitt is trying to acquire the Blackbird file from a Drayton employee.
As Jack and Dan discover that Ashford is gone, Ashford calls Hewitt, who says he'll send an associate to make the exchange. Then the hitwoman - who's been holding a gun to Hewitt's head - kills him.
Ruiz comes home and finds snitch Julius outside Dan's trailer. Julius explains that Dan asked him to stand watch in his absence.
Dan and Jack break into Ashford's house. He's not there. Dan leaves to question Drayton, while Jack searches the place and finds a pig-bodied corkscrew that he and Liz acquired on an early wine-tasting date, which he pockets. Then Liz arrives and accuses Jack of suspecting Ashford out of jealousy. Jack counters with Ashford's having purchased tickets to the Maldives Islands, where there's no extradition to the U.S. Liz phones Ashford, voices Jack's suspicions, and gives him Jack's description of the hitwoman.
When Ashford sees her arrive, he drives straight at her, and - dodging several bullets - escapes.
Dan goes to Drayton's country club, shows him a sketch of the hitwoman, and gets thrown out. When the hitwoman calls Drayton saying that Ashford was tipped off, he fires her, adding that the cops have her picture.
Ashford returns home, says that he's blowing the whistle on his company, and only Jack can help. Ashford claims that he found the file and asked Wallace to contact the Feds, but Drayton got to Wallace. Jack asks why Ashford didn't give it to Liz? Ashford replies that he didn't want to endanger her and that the file is stashed at his ranch.
Meanwhile, Samantha tells Dan that Wallace was killed at the hospital this morning. (We see Drayton suffocate him.) Julius then asks to use Ruiz's bathroom, and he spots the Peeping Tom, whom Ruiz tackles - and discovers is a guy from her yoga class!
When Ashford asks Jack for privacy while he opens the ranch's safe, Drayton arrives and shoots Ashford. Jack races in, gun drawn, and forces a standoff. Ashford suggests Drayton kill Jack, but the hitwoman bursts in, aiming pistols at both Jack and Drayton.
Dan drives up, blows a "safety whistle," and Jack swats the startled hitwoman's gun aside. As they trade punches, Drayton grabs the file and runs outside. Dan throws a golf club, knocking Drayton to the ground.
Jack escapes the hitwoman's chokehold by stabbing her in the foot with that pig-bodied corkscrew. Dan enters, wraps up the hitwoman, and finds Ashford hiding in the closet.
Back at the station, everyone is buying Ashford's whistleblower story. But when smug Ashford privately rubs it in, Jack decks him.
That night, Ruiz, Julius, Dan, Jack, and Samantha are sitting around Dan's trailer when Liz arrives and tells Jack that she discovered Ashford lied about hiding in the closet - which Jack would never do - so she broke up with him.