Mayfair struggles to keep Daylight under wraps as Jane and Weller go undercover as man and wife.
After a tattoo reveals that the Witness Security Program database has been compromised, Jane (Jaimie Alexander) and Weller (Sullivan Stapleton) go undercover as married assassins, potential buyers for the data. While posing as Weller's wife, Jane has a flashback that suggests she was married to, and then broke up with, the mysterious man with the tree tattoo. At a drop site, Jane and Weller are swept into a helicopter and cut off from the rest of the team. Once they secure the stolen data, they learn a second buyer wants it, so they steal his copy, blowing their cover. During the ensuing shootout, Zapata (Audrey Esparza) and Reade (Rob Brown) swoop in to save the day.
David (Joe Dinicol) tries to win Patterson (Ashley Johnson) back by investigating one of Jane's tattoos. At the Brooklyn Historical Society, he sees a mysterious redhead leave a message in the coded book he and Patterson found. He tails the redhead, but pays the ultimate price. His dead body is found in an alley later that night. Meanwhile, Carter (Michael Gaston) tries to get Zapata to plant a bug in Jane's apartment. She agrees, but later goes back on her word.
Certain that having Guerrero (Lou Diamond Phillips) in custody will blow the lid off of Daylight, Gaston orders Mayfair to make him disappear. Although Mayfair (Marianne Jean-Baptiste) wants to convince Guerrero to pretend he was actually an informant, Carter still has him killed to cover their tracks.