McNally and Diaz make an untimely arrest, which compromises a major heroin bust; Swarek goes undercover posing as the buyer with McNally as his girlfriend, to try and salvage the operation. Peck and Diaz, who are part of the surveillance team, search a seemingly empty warehouse. As they are leaving Diaz is stabbed and as Peck checks on him the door closes and they find themselves locked in a room. In an attempt to get out through an air vent Peck sees the heroin is being prepared for the deal. Swarek and McNally try to make the deal, however the dealer has other plans and Swarek is forced to leave to get the heroin from an undisclosed location. When McNally is told that the buyer's boss will be at the exchange, she realizes that Swarek's cover will be blown and calls back-up, blowing her cover in the process. Nash and Epstein notice that Peck and Diaz have failed to check-in from their location, leading them to believe that the warehouse is where the heroin is. Tactical teams arrive at the warehouse and successfully save Swarek, Diaz, and Peck and also take down the drug ring.