As they are in mid-argument, a car rips out of the garage – the teams immediately think it is Ben getting away.
Back at SBPD, Henry reprimands the teams for losing the lead. Lassie and Gus try to tap in synch to help themselves concentrate on the case. They realize that the car they found her body in was shared between Desiree and Ben – but they also determine that the car was rented not owned. Jules and Shawn see them tapping and make fun of them.
Shawn and Jules show up at a science research facility to find another lead. Shawn signs Jules up for a clinical trial to create a diversion, so as to peak into Ben's office. It works and he checks Ben's emails and finds an invoice for flowers he sent to his mother.
Gus and Lassiter are at the car rental place where they discover there was a tracking device on the rental car. They get the tracking I.D., and with that they determine that Ben has motive. But shortly after, Gus and Shawn get a bit of info that leads them to believe that Ben is not guilty. So Shawn and Gus decide to team back up. Now it's Shawn/Gus vs. Jules/Lassie – things are back to normal again. Shawn and Gus arrive at the coroner's office. They want to find everything out about the autopsy of Desiree. Woodson tells them there is a mark on her ankle – looks like freezer burn. He asks, "Why would a drowning victim show no signs of struggle?"
Then Lillian, the first lab tech, shows up at SBPD with some info on their case. Ben's name is officially cleared when she presents them with evidence that Ben was in the office at the time of the murder. Shawn recalls Desiree's mother talking about how Ben had cheated on Desiree. Then Shawn realizes they never found out whom Ben was cheating on Desiree with.
Woody determines that Desiree died from dry drowning – an overdose of anesthesia. Shawn immediately recalls the assistant at the science research – Shawn accuses her of being the other woman and the person that took Desiree out. But the woman says she's just an assistant and doesn't have access to the anesthesia.
Shawn then figures out the case – Lillian the lab tech was the one that killed Ben. They were lab partners – and she fells for him. Ben and Desiree split up – but Ben wanted her back. And Lillian didn't want that to happen. Lillian killed Desiree out of jealousy. Lillian admits it and she is arrested.