Sly 3 opens
in medias res one year after the events of
Sly 2: Band of Thieves:
Sly Cooper,
Bentley, and other unidentified characters are attempting a vault heist on an island in the Pacific Ocean. They are intercepted by Dr. M, the island's owner. Sly gives up his family's cane to save Bentley from a monster, but gets captured himself. While the monster crushes him, Sly's life
flashes before his eyes. He recounts his family's history and the events of the prior two games. He recalls meeting one of his father's colleagues, Jim McSweeney, who revealed to Sly the existence of the vault and that it contains the Cooper family's accumulated wealth built up over the centuries. Sly went to find the vault, only to discover Dr. M had built a fortress on the island in an attempt to enter the vault himself. Sly needed additional experts to get past Dr. M's extensive security; he needed to expand the Cooper Gang. The majority of the game is a large
flashback that recounts how Sly and Bentley recruited more members for the heist. They first sought to bring back
Murray, who had left the gang after taking responsibility for Bentley's paralysis resulting from the end of the previous game. He had begun studying
Dreamtime from a
Guru to find inner peace, and the Guru had sent Murray on a mission to clean the water in
Venice, Italy. Sly broke
Dimitri out of a local prison in exchange for Dimitri's help in locating Murray. Sly and Bentley learned that the local mob boss,
Octavio, was polluting the water with tar as part of a scheme to threaten the city into liking
opera again. They foiled Octavio's plan but he injured Bentley, leading Murray to defeat Octavio in battle to defend Bentley. Murray re-joined the gang but felt guilty about resorting to violence, so the gang traveled to
Yuendumu in Australia's
Northern Territory to allow Murray to reconcile his actions with the Guru. They discovered the Guru was captured by local miners who were tearing up
Aboriginal sacred sites in search of precious
opals. After freeing the Guru, he informed the gang that the miners had inadvertently awoken the Mask of Dark Earth, a sentient mask that makes its wearer a vicious, powerful giant. The mask latched onto
Carmelita Fox, who had continued her chase against the gang. The Guru assisted the gang in removing the miners from his land, freeing Carmelita, and destroying the mask. He joined the gang to continue Murray's training and return the favor for their help. In search of a robotics combat expert beyond his own abilities, Bentley met a Dutch mouse named
Penelope online. She agreed to join the gang if they could prove themselves by taking down her boss, the
Black Baron, in his flying competition. The gang traveled to
Kinderdijk,
the Netherlands and entered Sly in the competition. Dimitri, who was hired as a
color commentator, helped the gang sabotage the other teams—including one run by
Muggshot—in exchange for a favor later. Sly defeated the Black Baron, who was revealed to be Penelope in costume; she had donned the persona to get around the competition's minimum age requirement. With her time as the Black Baron over, Penelope joined the gang without hesitation. Bentley determined they still needed an exceptional demolitions expert and suggested recruiting Sly's former enemy, the
Panda King, much to Sly's dismay. Bentley explained the Panda King had forsaken his life of crime; upon meeting him in China, the Panda King elaborated that his daughter, Jing King, had been kidnapped by a local general,
Tsao, who was planning to
forcibly marry her. Sly and the Panda King reconciled their past to work together and save her. In the process, Murray recovered the team van, which had floated all the way from Canada in the previous game. After the gang rescued Jing King, Carmelita arrested General Tsao and escorted him to jail, while the Panda King left his daughter safely with her aunt and joined the gang to repay his debt. Dimitri emailed Sly to call in the favor he mentioned in Holland. He bought tickets for the whole gang to travel to Blood Bath Bay, a town in the
Caribbean Sea that maintained the ways of piracy. Dimitri was searching for his grandfather's scuba diving gear and the loot he had obtained from undersea wrecks, all of which was stolen by a local pirate. The gang successfully recovered the scuba gear, but another pirate,
Captain LeFwee, stole the loot and kidnapped Penelope. The gang worked together to rescue her from LeFwee's ship; during the rescue, Bentley freed Penelope from her cell, but LeFwee injured him. While he prepared to deal a final blow, Penelope took the opportunity to grab a sword and challenge LeFwee to a duel. She defeated him and the gang escaped the harbor. Bentley and Penelope became a couple while Dimitri, unprompted, informed the gang that he'd be joining them as their
frogman for the Cooper Vault heist. The flashback ends and the game returns to the present day, where Sly is still struggling in the grip of Dr. M's monster. Carmelita arrives on the island with mercenaries and battles the monster, intending on capturing both Dr. M and Sly. With both Carmelita and the monster distracted, Dr. M escapes while the gang rescues Sly. As he recovers, the gang works to retrieve Sly's family cane, the key to the vault, battling Dr. M multiple times in the process. Dr. M reveals to Sly that he also worked with Sly's father but, unlike McSweeney, he felt that he was mistreated and resolved to steal the Cooper fortune for himself. Sly recovers his cane and enters the vault alone while Bentley and Murray defend the entrance. Dr. M battles them before following Sly into the vault's Inner Sanctum. The two fight, causing the ancient structure to begin collapsing. Carmelita arrives to arrest them both. Dr. M attempts to shoot a blast of energy at her, but Sly jumps in between to protect her. Carmelita defeats Dr. M and checks on Sly, who appears to suffer from amnesia. He asks who he is, and Carmelita, taking the opportunity to rehabilitate Sly, chooses to say that he is her partner. They escape together while Dr. M, refusing to leave the vault he worked so hard to enter, dies in the collapse. The rest of the gang finds an alternate entrance to the vault marked by Sly's family cane and his classic calling card, realizing he's alive but didn't want to be found. When Sly does not return after a few months, the gang splits up to go their separate ways. Dimitri becomes a rich scuba diver; the Panda King returns to China to live near Jing King, who was happy to let him screen all of her future
suitors; Murray completes his training with the Guru and becomes a professional race car driver using the team's van; the Guru begins teaching his mystic art to a group of rock stars in New York City; Bentley and Penelope stay together, create a new Cooper vault with higher security,
and begin work on a time machine. One day, while Bentley is looking across the Paris skyline, he spots Sly and Carmelita on a balcony holding hands. Sly notices Bentley and winks, confirming he faked his amnesia to start a new life with Carmelita. ==Development and release ==