Ace Ventura (Jim Carrey) is a private investigator (self-conferred as a "pet detective") from Miami, Florida, who specializes in cases involving animals. While his methods seem to work effectively, he does not often get work and thus is behind on his rent, in addition to being a laughingstock at the Metro-Dade Police Department.At Joe Robbie Stadium, the mascot of the Miami Dolphins, Snowflake the Bottlenose Dolphin, is kidnapped in the middle of the night, two weeks before the team is due to play in the Super Bowl. Mr. Riddle, the team's owner, knows that football players can be superstitious, and therefore believes they will lose the Super Bowl for certain unless Snowflake is returned. He gives his Head of Operations Roger Podacter (Troy Evans) and Chief Publicist Melissa Robinson (Courteney Cox) the deadline of Super Bowl Sunday to find Snowflake, or they will be fired. Ace is hired onto the case, and he meets Melissa and Podacter before entering the dolphin tank in search of clues. Ace then searches the filter and finds his first clue: a rare triangular-cut orange amber stone. He eventually theorizes that the stone, a rare triangular-shaped amber piece, had fallen from a 1984 AFC Championship Ring. Ace then tries to find out whose ring is missing a stone by tricking players into showing their rings until his list of suspects is used up. Seemingly at a dead end, he mopes around Melissa's house while insulting her.
Melissa and Ace then learn that Roger Podacter has fallen to his death, and they go to the crime scene. Although Miami Police Lt. Lois Einhorn (Sean Young) insists it was suicide, Ace proves that it was murder. This embarrasses Einhorn and Ace is driven away because of it. While trying to figure out how Podacter's death is connected to Snowflake's disappearance, Ace learns of a former Dolphins player named Ray Finkle, whom Ace has not investigated. Melissa explains that Ray Finkle was a star kicker who was added to the team mid-season, whereas the photograph that Ace has used as a reference was taken earlier that same year. Finkle had missed the potential game-winning field goal kick at the end of the Super Bowl XVII that year, causing the Dolphins to lose to the San Francisco 49ers. After the season, Finkle's contract was not renewed and his reputation was destroyed. Later that night, Ace takes Melissa back to his apartment where they have sex, to the point of exhaustion.
The next morning Ace drives down to Finkle's hometown in Collier County, Florida to meet the football player's parents at their home, which is defaced with anti-Finkle graffiti written by irate fans over the years. Finkle's mother is senile, and his father is a suspicious, shotgun-wielding old man who confides to Ace that his son was put into a mental institution in Tampa after his career ended; Finkle later escaped from the institution and is still at large. Mrs. Finkle then shows Ace Ray's bedroom, which contains a shrine-like construction declaring his hatred of Dan Marino, and while in Ray's room, Mrs. Finkle also shows Ace footage of the missed kick from Super Bowl XVII. During the kick, Dan Marino held the ball after it was snapped; in the aftermath of Super Bowl XVII, Finkle blamed Marino for the miss, claiming he held the ball "laces-in" when he should have held it "laces-out." Ace then calls Melissa to warn her that Marino is in danger, but Marino is kidnapped before he can be alerted.
Ace meets with Lt. Einhorn and alleges that Marino and Snowflake's kidnappings were connected and that Finkle was involved, claiming that the Dolphins gave Snowflake Finkle's old number and taught him how to kick a field goal, which Finkle took as an insult, and that Finkle has waited for years until the next time the Dolphins return to the Super Bowl to extract his vengeance on the Miami Dolphins franchise. Einhorn then comes onto Ace. The two share a kiss (during which Ace feels something that he assumes to be Einhorn's gun digging into his hip) and tells him she will now handle the rest of the investigation. Ace, still not satisfied with Einhorn's efforts to find Marino and Snowflake, pretends to be mentally challenged to gain access to the institution by that Finkle escaped from. Ace wears a pink tutu along with messing up his hair. There, Ace discovers an old newspaper amongst Finkle's discarded belongings, stating that Lois Einhorn was a missing person whose body was never recovered. This bombshell eventually leads Ace to the realization that Einhorn not only killed Podacter, but Lois Einhorn is Ray Finkle in disguise. His sense of triumph is quickly replaced with disgust after realizing that he had kissed someone he perceives as a man, and that the "gun" he felt digging into his thigh earlier was actually the Lt.'s erection.
Super Bowl Sunday arrives. Ace follows Lt. Einhorn to a remote warehouse by the docks, and the two engage in a short struggle before all the Miami Police force arrives to arrest Ace on Einhorn's orders. They are stopped by Melissa, who has Emilio held hostage at gunpoint. Einhorn screams at the police officers that Ace is behind it all and that he kidnapped Snowflake and was trying to kill Marino and her. Ace explains Einhorn's motives and claims that Einhorn is actually Ray Finkle. Einhorn denies Ace's accusation, which leads to Ace trying to find proof by first trying to remove the Lt.'s hair thinking it to be a wig - it turns out to be real. Next, he rips open the Lt.'s blouse to find perfect feminine breasts. In a last ditch effort, Ace rips off the Lt.'s skirt assuming there to find his penis, but instead appears the normal figure of a woman. Just as Ace is about to give up, Marino alerts Ace of something he can see behind Einhorn. Ace then spins the Lt. around to reveal Einhorn's/Finkle's penis tucked between her/his legs. It is revealed that Einhorn killed Podacter because he discovered that Einhorn's true identity is indeed a man. The whole police force reacts in disgust, apparently because she had made out with all of them as she did with Ace. In a rage, Einhorn makes one last attempt to kill Ace but he flips her into the dolphin's tank. Einhorn is then arrested for all of her crimes.
The movie ends with both Marino and Snowflake returning to the Super Bowl game between the Miami Dolphins and the Philadelphia Eagles at halftime. Ace suddenly spots the albino pigeon he was chasing earlier in the film on the Dolphins' sideline, perched on top of a cooler of Gatorade. He attempts to capture it but Swoop, the Eagles' mascot, scares it away. Enraged, Ace argues with the mascot and the two end up in a fist fight whilst Ace is thanked, on the JumboTron, for saving Marino and Snowflake.
Ace Ventura : Pet detective
