Andy McDermott is the main protagonist in An American Werewolf in Paris. He is an american tourist, and the husban of Serafine Pigot.
In 1997, Andy and his friends, Chris and Brad arrive in Paris with hopes of bungee jumping off of the Eiffel Tower. Their first night there they encounter a young woman named Serafine Pigot, who is prepared to jump off of the Eiffel Tower. Andy tries to talk her down and as she jumps, he daringly jumps after her. Andy catch's her and lets her lightly drop when they where just feet off of the ground. Andy catch's her shoe as she drops, but the bungee cord slings back into the tower knocking him out. Andy wakes up in the hospital and sends Chris and Brad to find a suicide note she had in her hand.
After recovering, Andy finds Serafine's house, and gives her back her shoe and attempts to ask her why she tried to kill herself. After a brief conversation, she hesitantly agrees to go on a date with him. Their date is filled with awkwardness, such as Serfine finding a condom placed by Andy's friends (who followed them on the date). Serafine leaves after she overpowers a large man who was provoked by Andy. Andy once again tries to talk to her and by the time they get to her house, they run into an acquaintance of Serafine's named Claude. Claude also owns a nightclub called "Club de la Lune" and invites them to his club saying he loves Americans.
At the club, Andy and Brad hang around while Chris offers to check on Serafine. Little do they know, the club's staff (except the bouncer) are all werewolves that use the club to kill guest's. When Serafine hears about the party, she locks Chris in the basement and tries to rescue Andy and Brad. She takes Brad and Andy to an escape route in the catacombs, whilst being followed by Claude and his boys. Serafine begins to transform and she has Andy run away after he and Brad get separated. Brad is killed by the werewolves and Andy is bitten as he escapes.
Andy wakes up in Serafine's bed, confused. He see's Chris (who spent the night locked in Serafine's basement and had a terrifying encounter with a werewolf.) outside the window telling him to run away. Serafine allows Andy to feel her breasts to calm him down while she tells him that she is a werewolf and he is now one to. Andy naturally doesn't believe her but becomes scared when he sees the ghost of Alex Price, Serafine's mother. Afraid, Andy runs off.
Over the next several days, Andy has encounters with Brad's ghost. Thinking he is going crazy, he ignores him. Andy's odd behavior attracts attention from a detective in the club's massacre, who begins stalking him. Andy begins to gain an animal instinct as he also gets the attention of an american girl named Amy, who sweet talks him to going to the cemetery where they nearly have sex but a transformation begins to trigger and Andy runs off, much to Amy's anger. The werewolf Andy stalks the cemetery and kills Amy aswell as the detective and his dog. Andy wakes up surrounded by police and also find's out he is a suspect in the club's massacre as he was one of the few survivors, but Andy eludes arrest.
Andy is shadowed by the ghosts of Brad (who wants to help his friend) and Amy (who wants vengeance for her death). Andy has a run in with Claude and his gang, who take him to an abandoned church, telling him about their society and they wish to have him join, but to do so he must kill his abducted friend Chris. Andy refuse's angering Claude, but Andy is rescued by Serafine who takes her back to her house.
At their house they find, Serafine's basement was raided and her stepfather killed by Claude. Serafine finally tells Andy of why she tried to kill herself. Her stepfather, Thierry Pigot, was a doctor who was making a cure for lycanthropy. Rather then cure her, it caused an immediate transformation resulting in Alex's death and Doctor Pigot getting cursed. Andy express's his condolences and begins to kiss her, until Andy remembers advice from Brad causing him to realize the cure is to eat the heart of the werewolf that bit him, which he believed to be Serafine. They also discover Claude's intentions to use the "cure" to start another massacre.
Serafine and Andy infiltrate the club while police raid the party and attempt to arrest the socity as they turn into werewolves. Andy and Serafine kill off many werewolves then chase the remaining werewolves into the catacombs, while the police follow them. In the darkness, many of the police officers are killed by the werewolves while Andy and Serafine continue to hold their ground. Serafine transforms to fight off an attacking werewolf and in a case of mistaken identity shoots and wounds Serafine. He express's remorse for this and Serafine begs Andy to kill her, but Andy allows the police to recover her while he faces the last werewolf - Claude. In the ensuing confrontation, which makes it's way onto a subway train. Claude's dose runs out and he returns to his human form. Andy takes the next dose and transforms, killing Claude, eating his heart and curing him. Meanwhile, Serafine miraculously survives.
Several months later, Andy and Serafine move to New York where they are married of the Statue of Liberty by Chris. The ring accidentally slips out of their hands and they bungee jump after it together.