This is it Sly, the gang's assembled and are in position to help you get up to that vault. For the rest of the operation, you are "the ball.""The Cooper Vault" was a job for Sly Cooper in "Beginning of the End" of Sly 3: Honor Among Thieves.
― Bentley making sure that Sly Cooper is ready to infiltrate Kaine Island[src]
Sly infiltrated the island's outskirts, taking out three guards in the process. After making his way to a small section of the island, Bentley briefed him on the mission, making sure that the rest of the gang was ready. Afterwards, Sly made his way further into the island, until he was obstructed by several guards on support beams blocking his path along a ledge. In response, Agent Heartthrob used a Yank 86 to clear the obstruction.
Not long after, Sly came to a gap that was too large to jump across. Agent Old Rock was deployed to knock down a nearby satellite tower so that Sly could Rail Walk across the gap. Soon after, Sly came across an air vent that directly led to the ceiling of Dr. M's underground lab. Agent Monarch launched a firework at the vent to bust it wide open, allowing Sly to use it to gain access. Once inside, Agent Deep-Six used his harpoon gun to destroy the force fields blocking Sly's path, which began to slowly flood the lab.
As Sly made his way to the top of the lab elevator, Dr. M and a henchman named Richards entered the lab and approached the elevator. Dr. M and Richards started a seemingly harmless conversation, with M asking Richards how his family was doing. Sly made it to the elevator just as Dr. M and Richards did, and the elevator began to rise to the surface. On the ride up, Dr. M told Richards that he wouldn't be seeing his family again, as M poisoned his drink during the lunch break. Dr. M explained that Richards forgot to change the code for a newly-installed security system from the default "1-2-3." A terrified Richards promised to do better, but the doctor replied that Richards was seconds from death, at which point he tumbled over and died. Just as he reached the surface, Dr. M then received a call about water leaking into the lab, and headed back down the elevator to investigate. Sly jumped off the elevator just before it went down so that he could continue to approach the Cooper Vault.
Bentley told Sly that he was on his way to meet Sly at the vault for the hauling of the vault's loot. Sly made his way across several ropes towards the vault, but accidentally set off the alarm in the process, causing turrets to open fire on him. He reached the security system and inputted the 1-2-3 code, causing the vault's security to deactivate. Sly inserted his cane into the vault lock, and the vault proceeded to open. Just before the vault could open all the way, a missile exploded near Sly, shutting the vault again. The shooter was revealed to be none other than Dr. M himself, flying a jetpack. After a brief confrontation, Bentley snuck up behind the doctor and fired a sleep dart at him, disorienting him long enough for Sly and Bentley to attempt their escape. However, just before reaching their ship, Dr. M appeared with a giant mutant primate under his control, and captured Bentley. Sly saved Bentley by tossing his cane into the mouth of the monster, causing it to release Bentley. However, the monster soon launched the cane into the sea, before grabbing Sly. With the monster beginning to crush Sly, an outgunned Bentley was forced to escape to the other Cooper Gang members.
Sly's life began to flash before his eyes, with the flashbacks starting from just before the Fiendish Five killed his parents. Eventually, the flashbacks started to recount how he and Bentley expanded the Cooper Gang for the now ill-fated Cooper Vault heist, starting with Murray being re-recruited.
- During the binocucom introduction, the identities of all of the Cooper Gang members, except for Sly and Bentley, are hidden in order to prevent spoilers.
- However, Murray's subtitle is still in his trademark pink color.
- Bentley and Murray are the only Cooper Gang members whose code names, if any, are never mentioned during the heist.
- Murray is the only Cooper Gang member who did not get to directly participate in the heist before it broke down. The only thing known about Murray's role during the heist was that he was the "recovery team."
- During the section where Sly has to wait for the sets of vertical lasers to be turned off, Dimitri can clearly be seen swimming on the other side of the glass wall to Sly's left.
- During the chase scene, Bentley and Sly jump down through the lasers without getting hurt.
- This is the only intro mission in the Sly Cooper series that takes place in medias res.
- This is also the only intro mission to involve a boss fight, though the fight is unwinnable.
- This is also the only intro mission where Carmelita Fox does not make an appearance.