The 3rd game in the series would come out just a year after the sequel in 2005. The game had very similar gameplay to the 2nd, with a new riveting story and journey for the gang to embark on. The game begins on Kaine Island as Sly is trying to get into the Cooper Family Vault, with new members of the gang for this mission that are kept a mystery. He runs into Dr. M, the main antagonist of this game, who with aid of his own huge, controlled monster has Sly on the verge of defeat when Sly’s life flashes before his eyes. He talks about how his father’s old partner McSweeney gave him the info on the vault, stating that only a Cooper could open it. When Bentley and Sly went to scout it out they found that Dr. M had set up shop for years trying to get it open, and Sly said they would need a team of world class criminals to get inside of Dr. M’s stronghold and into the vault.
The first stop was getting Murray back on board, as he had left after the events of the 2nd game because he blamed himself for Bentley’s injury. He had went to find his spiritual self with the Guru and was at Venice in part of his walking journey to find himself the Guru had sent him on. The gang was able to bring Murray back in after stopping local criminal Octavio, and a black tar water crisis he had caused. They would then go on recruit the Guru that Murray had been learning from, who agreed after the gang helped him get back his staff and moon stone and save his home in the Australian Outback. Next, they went for tech specialist Penelope, who said that she couldn’t join unless they took down the Black Barron since she was working for him, however it turned out that she WAS the Black Barron. After the gang defeated her, she agreed to join and would later become Bentley’s girlfriend. Next was former villain in the 1st game, Panda King, who would operate as a demolitionist and explosive expert. He agreed to join gang after they helped him save his daughter from the insufferable General Tsao. Lastly, while recruiting Penelope the gang ran into another former enemy Dimitri. Who asked for a favor after helping them get out of a sticky situation at the time, and was calling it in to help get back his father’s diving equipment. After the gang helps get it back from the evil pirate who stole it, LeFwee, Dimitri joins the gang.
The flashback ends and it then jumps back to Sly in the clutches of the monster, before he saved by the entire gang plus Carmelita (Who yes, was still chasing them the whole game). They then work to get Sly inside the vault and succeed, and Sly was able to experience all the treasure, riches, items, and everything else his long line of ancestors had put in there. However, Dr. M wasn’t done, Bentley and Murray did what they could to hold him off. In this confrontation we also learn that Dr. M was the brains and 3rd member of Sly’s Father’s gang alongside him and McSweeney. After guards show up to occupy Bentley and Murray, Dr. M chases after Sly using a tracker he placed on his cane. They do battle inside the vault, with Sly ultimately coming out on top. Carmelita then shows up, claiming she intends to arrest both. After Dr. M sees the feelings Sly has for Carmelita, he sets his sights on her. Sly jumps in the way of a huge blast which sends him flying. Carmelita then finishes off the doctor before going to check on Sly, who appears to have amnesia after the blast. Carmelita lies to him and claims that he is her partner “Constable Cooper”, which Sly believes and they leave the island together. The gang then goes their separate ways with Dimitri becoming a famous diver, Panda King living two doors down from his daughter, Guru continuing his teachings, Murray looking to become a professional racer, and Bentley and Penelope begin working on a time machine. In the post-credit scene, Bentley is seen spying on Carmelita and Sly, where Sly looks directly at Bentley’s cam and winks. Indicating that he faked his amnesia all along to be with Carmelita.