Jonathan Moore, Anthony Edwards, an 18-year-old UCLA veterinary student, is an expert at Gotcha, a popular Assassin-like game where students chase each other on campus using paintball guns. For spring break, he and his roommate Manolo, Jsu Garcia, travel to Paris. In a quiet café, Jonathan meets Sasha Banicek, Linda Fiorentino, a 24-year-old Czechoslovakian woman, and later loses his virginity to her. Instead of going to Spain with Manolo, Jonathan accompanies Sasha to West Berlin to spend more time with her.
Sasha warns that she must go to East Berlin to pick up a package, as she works as a courier. One night, after arriving in East Berlin, Sasha slips out of their hotel and meets a German man who tells her the location of the pickup. Unbeknownst to them, Vlad, a Soviet agent, is monitoring her. The next day, Sasha tells Jonathan that if she ever instructs him to meet her at the Café Friedrichstrasse, it means he must immediately leave East Berlin, and she hands him a package with a strudel. Vlad follows them, but Sasha escapes. The German man orders her to use Jonathan to deliver the package to West Berlin. Sasha meets Jonathan at a subway station, slipping the object into his backpack and saying she will meet him back at the hotel. However, she later calls him to meet at the Café Friedrichstrasse.
That night, as Jonathan rushes to Checkpoint Charlie to cross into West Berlin, Vlad arrives at the border to search for him. Sasha is caught by the East German secret police and strip-searched, but nothing is found on her. Vlad chases Jonathan as he crosses the border and enters West Berlin just ahead of capture. Once there, Jonathan finds his hotel room ransacked and his traveler's checks stolen. Vlad and his henchmen eventually locate him at the Spandau Citadel, where a woman who asks for the object Sasha gave him is mistaken for the one who holds it; Jonathan hands her the strudel, and Vlad shoots her. The pursuing agents chase him through the Citadel; he leaps into a water canal and escapes, stumbling upon a German punk rock band headed for Hamburg who give him a ride to the airport.
Back in Los Angeles, Jonathan thinks he has left the nightmare behind, but Vlad leads a band of Soviet agents to the city. Jonathan discovers the object Sasha slipped into his backpack—a film canister. He tries to tell his parents what happened in Germany, but they do not believe him and think he is a drug addict. He reaches out to the CIA, recounting Sasha's role and the film. After a brief run-in with law enforcement for ramming a car, he returns to find his apartment broken into and looted.
The CIA, Steve Eastin, directs that he bring the film canister to them. At the CIA's Los Angeles headquarters, Jonathan is surprised to find Sasha working there. He enlists Manolo's help to stage a meeting with Sasha at UCLA and separate her from the CIA agents. Sasha reveals that she is actually Cheryl Brewster, a CIA agent from Pittsburgh, before Vlad and his men appear and chase the pair through the campus. In the frantic escape, Jonathan grabs a tranquilizer gun from the veterinary sciences building and uses it to incapacitate their pursuers. The Soviet agents are captured, and the CIA thanks Jonathan for recovering the film. Cheryl/Sasha expresses a hope to continue their relationship, and they share a kiss.
After these events, Jonathan chats with an attractive student who had previously rebuffed him; she rejects him again. As she walks away, he aims the tranquilizer gun at her and shoots her in the rear.
