Ben 'Finn' Finnegan (MATTHEW McCONAUGHEY) is a treasure hunter whose obsession with finding an early 18th century shipwreck off an island near Florida has led to the dissolution of his marriage to Tess (KATE HUDSON). She once shared his desire to locate the long lost treasure, but has had enough and wants to go back to academia, and thus goes through with the divorce proceedings to which, naturally, he's late.
He has good reason, however, as some local thugs, Cordell (MALCOLM-JAMAL WARNER) and Curtis (BRIAN HOOKS), who work for rapper/gangster Bigg Bunny (KEVIN HART), tried to send him to the sea floor attached to an anchor. It seems Finn owes Bigg Bunny a lot of money, and the fact that the treasure hunter and his diving partner, Alfonz (EWEN BREMNER), have possibly found the shipwreck means they want him out of the picture.
In the meantime, Tess has taken a job as the steward on a huge yacht owned by mega-millionaire Nigel Honeycutt (DONALD SUTHERLAND) who's dismayed that his airhead, party-hearty daughter, Gemma (ALEXIS DZIENA), is on the cover of various gossip magazines. When Finn ends up saving Gemma's hat out at sea, he draws the Honeycutt clan into his quest, much to the initial dismay of Tess who isn't happy to see him.
That sentiment is shared by salvage diver Moe Fitch (RAY WINSTONE), Finn's former mentor and business partner who's been hired by Bigg Bunny to find the wreck. With Tess now back on board, Finn and his impromptu team do what they can to beat the others to that, all while having to deal with Bigg Bunny and his newest and far more dangerous henchman, Cyrus (DAVID ROBERTS).