Nate returns from Las Vegas to meet with an investor to expand his limo company, and is questioned by Detective Paxson, who tries to convince Nate to betray and reveal everything about Michael's private investigations. Although Nate remains firm and refuses, Michael and the team plan to get Paxson into trouble with the Mayor's office and make her break off her investigation. As Michael goes to his car, he is surprised by Tyler Brennen, an arms trader and dealer who proceeds to disable Michael's car (due to holding a grudge against Michael since Season 2; "Sins of Omission"). Brennen has returned to Miami, after succeeding in getting rid of his South American pursuers by anonymously financing and supplying a private, bloody war between them and a rival cartel. He has taken on the role of Nate's investor and brought a Sicilian enforcer, "The Butcher", who is currently in a meeting with Nate. Brennen threatens to have Nate killed if Michael doesn't help him pull off an elaborate heist. Michael proceeds to do so, eventually realizing Brennen plans to steal a government weapon, but gradually lays an elaborate plan, with the help of the team and Barry, to destroy Brennen's presence in Miami. To force Michael to finish the job, Nate is brought to the heist by Brennen and is subsequently shot and injured. Michael, refusing to steal the weapon, is forced to spring his trap: Sam and Fiona blow up Brennen's house, and Barry tricks Brennen into giving him his financial info and pretends to drain his accounts (Barry pretends to be the bank manager). Brennen is undeterred, until Michael claims to have put an assassin in place to kill Annabelle; Brennen's secret young daughter, who is away at private school in Switzerland. Terrified for his child's safety, Brennen departs, but not before saying they will meet again. In the end, it is revealed the plan to get Paxson into trouble failed: it only succeeded in getting Paxson's partner suspended, driving Paxson to declare to Michael she will play just as under-handed.