Chow has double-crossed them. The villa they broke into (to steal back the gold bullion) did not belong to Chow, but was in fact Marshall's (John Goodman) - meaning Marshall has now lost all of his money to Chow.
Marshall bails them out of prison, and gives them a new assignment to find Chow. He kills Black Doug as a warning, and lends them the limo.
Alan has a great idea to track Phil's phone using an App - and they follow the coordinates back to Vegas to find the minivan parked outside a pawn shop. Alan flirts with the shop owner to find out that Chow is holed up in one of the hotels with a load of escorts.
They stop by Alan's old flame, where Alan bonds again with his little friend, and learn that he is at the Penthouse suite at Caesar's Palace.
Alan and Phil break inside through the staff entrance and get to the top floor. They make a ladder out of bedsheets and climb down to the Suite where they surprise Chow.
Chow escapes out the window - and parachutes to safety.
Stu follows in the limo -- and Chow cannot help but land on the windshield. They soon crash and Chow is knocked unconscious. Stu bundles him in the trunk, picks up his friends, and they meet Marshall and his bogyguard in the desert.
Chow wakes up and begs them to let him go, but the boys don't listen.
Marshall hands back Doug - then with his bodyguard takes out a gun and unloads into the trunk of the limo. He opens it to find that Chow isn't inside -- instead Chow appears from the sunroof and shoots both men in the back.
He thanks Alan his friend for letting him out. Alan has had time to think, and tells his old pal that they shouldn't be friends anymore.
As the Wolf Pack prepare to leave Vegas, Alan asks to make his own way home - but first stops by the Pawn Shop.
It's Alan's wedding! And the Wolf Pack are back as his entourage.
After the credits...
Best bit of the movie. There's carnage in the hotel suite. There's a motorbike that has crashed through the wall, and Phil and the others wake up with stinking hangovers. Stu enters from another room ... wearing knickers ... and with breasts! Alan slowly figures out that the wedding cake was a gift from his old friend, and would have been drugged.
As they are freaking out, a naked Chow appears from the next room...!