Chaperone

Chaperone is the first mission for Salvatore Leone in Grand Theft Auto III.

Note that once this mission becomes available (after Salvatore's Called A Meeting), all the other Mafia bosses are unavailable until this mission is completed.

Mission
Pick up Maria from Salvatore's mansion, and take her down to the waterfront to get some party treats. From there, drive her to the warehouse party at the docks, and wait while she goes inside. When the police raid the party, take Maria safely back to the mansion.