Spoiler Warning:Plot details, ending details, or both are in the text which follows.
This is a list of all missions in Grand Theft Auto III, sorted by type, island and mission-giver. There are 51 storyline missions, 17 phone missions, 4 off-road missions, 4 remote-controlled Missions, and 1 side mission for a total of 77 missions.
Claude is betrayed by his girlfriend Catalina when she shoots him during a bank heist, leaving him for dead. He survives and is arrested, but on the way to the penitentiary, the Colombian Cartel ambushes the convoy to kidnap another prisoner, destroying the bridge in the process and isolating the island of Portland from other parts of Liberty City, and he and another prisoner named 8-Ball manage to escape. With his new allies, he eventually forms a connection with the Leone family by destroying the neighboring Triads and Forelli family. He finds out that Catalina has become a co-leader of the Colombian Cartel, and eventually destroys their ship filled with the drug SPANK. However, Salvatore Leone, the Don of Leone family, has grown paranoid and no longer trusts anyone. So when his wife, Maria, lies and says she and Claude are having an affair just to spite him, Salvatore sends Claude to his death by planting a bomb in a car he ordered Claude to take away. Maria finds out and warns Claude just in time and, along with Yakuza leader Asuka Kasen, they leave Portland on a boat to Staunton Island.
Portland has 22 missions and eight phone missions for a total of 30 missions.
Cutscenes depicting Catalina's betrayal of Claude, and the explosion which leaves Portland isolated from the rest of the city and Claude's escape with 8-Ball.
Claude is now a rogue from the gangs in Portland, with the Leone Family and the Triads after him, and begins making a new connection in the Yakuza. He assassinates Salvatore to prove he is no longer working for him, and he is introduced to Asuka's powerful brother Kenji and a corrupt policeman named Ray who helps him in exchange for doing his dirty work. Ray introduces him to Donald Love, a billionaire real estate mogul, who Claude helps as well for the benefit of Love and his company. However, to start a gang war and lower the real estate price of land Love wants, he steals a Colombian Cartel vehicle and kills Kenji, igniting a war between the two. He eventually finds Catalina again, who kidnaps Maria, kills Miguel and Asuka, and ransoms Maria for $500,000. Staunton Island has 26 story missions and nine phone missions for a total of 35 missions.