We open on Shawn and Juliet's new apartment. They have just moved in together and are hosting a housewarming party. Among the people in attendance are Juliet's mom Maryanne and her stepfather Lloyd, an accountant. Shawn thinks it would be a great idea for Henry and Lloyd to become friends. Juliet agrees, but doesn't think they should push it; she thinks they should let a friendship between the two happen naturally. But Shawn doesn't listen and decides to go ahead and set up a lunch date for Henry and Lloyd.
Meanwhile, we learn Gus is still dating Rachael and appears to be getting along well with her son Maximus -- so much so that Gus talks about him as if he's his own son, even though they've been dating for a short time. But Shawn doesn't buy it; he thinks Gus is just pretending to be okay with having a girlfriend who has a kid. Later, Shawn's observation is confirmed when Gus admits that he's not ready to be a dad to Maximus. But Gus doesn't want to stop dating Rachael; he just needs more time to get used to the idea of having an instant family.
Henry is on his way to meet Lloyd for lunch, the man-date that Shawn had set up for them, when he gets a call from Lloyd saying he's going to be late because he has to pick up a package. Henry offers to pick it up for him, as the mailbox place he is referring to is in his neighborhood. At the mailbox place, Henry picks up the package as promised. However, he makes one fatal error; he didn't follow Lloyd's specific instructions for retrieving the package. Henry says Lloyd's name out loud and the next thing Henry knows, he's being chased by Hispanic men with guns. Suddenly Lloyd shows up in a car, urging Henry to get in.
Lloyd explains that he's had some shady dealings in the past, namely a large gambling debt, and that he wants to turn over a new leaf. He wants to start fresh, erase his criminal past and forge a relationship with Juliet. But he knows that those things will never happen if he doesn't settle a debt - a debt involving the package Henry picked up for him. At this point Henry is freaking out, but ultimately he agrees to tag along. But Henry gets way in over his head when he realizes that Lloyd has talked him into flying with him to Mexico to return the package to an old friend. Henry also realizes they aren't headed to an airport to board a commercial airline. In fact, Lloyd has taken Henry to a private airfield where Lloyd himself will be piloting the plane.
Meanwhile, everyone at the SBPD has gotten word of the shootout at the mailbox store, the stolen car and the stolen plane at the airstrip. From the description of where the plane is headed, Shawn remembers seeing Lloyd researching that exact same location at the housewarming party. Shawn tells the group that Henry and Lloyd are headed to a town on the Baja of Mexico.
When Lloyd and Henry arrive in Mexico, the policia are there waiting to arrest him; Lloyd has been essentially banned from Mexico for his many indiscretions and Detective Lamas, who bears a striking resemblance to Lassiter, is there to bring him into the station. At the station, Lamas predicts that Lloyd is in Mexico to retrieve some engraving plates that were stolen from the United States Mint recently. He knows that Lloyd's old friend Pablo Nunez, the leader of a well-protected Mexican crime syndicate, has had his eye on the plates too. Lamas predicts that Lloyd is in Mexico to deliver the engraving plates package to Pablo. Lloyd promises that isn't the case. Lamas thinks Lloyd is bluffing and opens the suspicious package he's been eyeing. He reveals a simple pair of cufflinks and has no choice but to let them go.
Later, Lloyd and Henry are captured by Pablo's men and are brought back to his compound. Pablo asks Lloyd if he has brought the package. Lloyd presents the cufflinks and Pablo is beyond satisfied. These were Pablo's father's cufflinks and he has been looking for them for years.
Shawn, Gus and Juliet arrive in Mexico and head to the police station to get a lead on where Lloyd and Henry could be. From the evidence they have seen so far, they believe that Henry and Lloyd have been kidnapped. Lamas says that if anyone was to kidnap them, it would have been Pablo.
Back at Pablo's compound, Henry is shocked to see that Lloyd has found the US Mint plates hidden there and that Lloyd has subsequently stolen them. They both escape from Pablo's compound with armed henchmen on their tail.
Ultimately, they are unable to escape and are brought out to the desert to dig their own graves. Shawn, Gus and Juliet follow a lead to where Henry and Lloyd are. They watch the scene play out through binoculars, and Shawn realizes that Pablo has the U.S. Mint engraving plates.
Just then, one of Pablo's henchmen points his loaded gun at Shawn, Gus and Juliet. They are captured and then forced to dig their own graves right next to the fresh graves Henry and Lloyd have dug. Lloyd tries to cover up the real reason why he's in Mexico so that Juliet doesn't find out, but she already knows the truth about Lloyd's shady gambling history. Just when the group thinks their time has run out, Lamas and the policia show up and save them.
Lloyd stays in Mexico because he needs to fly the plane back to the states. But the rest return to Santa Barbara via car. Once they return, they think everything is all tied up until they get a call from Lamas saying that Lloyd has stolen the U.S. Mint plates from them. Juliet is especially upset by this news; she knew Lloyd would never change.
Shawn then flashes back to the surveillance footage from the mailbox place. He remembers seeing a Hispanic man, then realizes that he's the same guy he saw working at the Mexican police station under Detective Lamas. From this, Shawn knows that Lloyd has been set up by Lamas and that Lamas is the one who wanted the plates for himself all along; he just needed a patsy to pin the stolen plates on and Lloyd was the perfect candidate.
The group head back to Mexico to stop Lamas from killing Lloyd. From a distance they see Lloyd running away from Lamas and his armed men. They gun Lloyd down and the gang is horrified. They rush to Lloyd's aid and discover that he's actually still alive and had been wearing a bulletproof vest this entire time. He would never go to Mexico without one.
Even though Lloyd put Henry in danger, they bonded as friends anyway. In the last scene, we see them fishing together. Henry wears a bulletproof vest, saying he would never hang out with Lloyd ever again without one. Lloyd agrees that is probably wise.