Engines
performed by Gary Go

Jessica and Harvey confront Darby with the fact that Stephen ordered the murders, and Darby admits he found out after the fact and did nothing, for fear it would harm Ava. They get him to fire Stephen, but what he is honestly able to testify cannot prove Stephen's guilt. When Harvey calls Stephen to the stand, he fails to convince Cameron of Stephen's guilt and reduces Ava's chances still further. Harvey appeals to Cameron's desire for justice as well as victory, having Mike bring in Clifford (an innocent man that Cameron once convicted for murder). Darby advises Jessica to put aside her anger, and she does, reconciling with Harvey and working with him on an ultimate solution to Ava's problem. Darby agrees to plead to obstruction of justice (getting five years' probation) and testify against Stephen. Cameron takes the surer conviction and drops charges against Ava, while Donna watches Stephen get arrested for murder. At the last moment, Darby discovers that with his probation he also loses his license to practice law in the US, therefore allowing Jessica to push for a dissolution of the merger. Back at the office, the now cat-less Louis lashes out against the associates, then goes to Harold's office to berate him about his testimony in the mock trial. Louis and Harold enter an escalating battle of legal action and intimidation, and Rachel confronts Louis over the depth of his resentment. He explains that his failure to train Harold reminds him of his own failure and the bullying he suffered. Rachel offers that Louis has bullied Harold in the same way. When Harold finally concedes the battle, Louis instead agrees to a compromise that will make Harold look good, swearing Rachel to secrecy about this unusual mercy.

Molly is kidnapped and used as bait, while Jonas is looking into a possible Russian terrorist cell.

Paige Hobson was last seen sneaking out of her office at the same time as an NYPD detective was asking her boss to direct him to Paige for a routine inquiry. To the team's surprise, the NYPD detective turns out to have been an imposter, causing them to question why Paige chose to run from this mystery man, what he wanted, and if he caught up with her. Further investigation uncovers that the seemingly upstanding and socially conscious Paige was involved in a lucrative identity theft ring with close ties to a terrorist on a watch list who was recently seen in New York with her. Meanwhile, the remaining team members are gravely concerned about Vivian, who is undergoing open-heart surgery on that very day. After receiving good news about Vivian's condition, Danny and Martin, transporting a suspect to another location, suddenly find themselves in the middle of a deadly shootout.