Tom and Jerry Meet Sherlock Holmes

In Victorian London, an unseen criminal begins masterminding a perfect plan on paper, which involves a robbery. During the theft, three cats steal a pink diamond and deliver it to a mysterious horseman, causing the authorities to pursue the culprits. The scene sets the stage for the series of crimes and mysteries that unfold throughout the story.

A robbery takes place where the three cats steal a pink diamond. Constables spot them attempting to escape, leading to a chase across rooftops. The cats manage to evade capture and give the stolen diamond to the mysterious horseman, emphasizing their involvement in the criminal plan.

Dr. Watson visits Sherlock Holmes at 221B Baker Street, informing him of the recent theft. Holmes then calls upon his pet mouse Jerry to get the latest news from the Times, setting into motion his investigation of the diamond theft and related crimes.

Holmes, along with Watson, visits the Bruce Nigel Theatre where they learn about Red, a performer being blackmailed. Holmes suspects Professor Moriarty as the mastermind behind the blackmail and plans to target the Star of Punjab diamond, which is sensitive to sunlight.

Guarding the Star of Punjab at the embassy, Spike and Tyke are inattentive, allowing three cats to steal the diamond. The cats leave a small button behind and escape through a tunnel, prompting Holmes, Watson, Tom, and Jerry to investigate further.

Holmes and Watson discover the button's origin while Tom and Jerry track the tunnel. Meanwhile, the police wrongly suspect Red, and a chase ensues involving Butch, Droopy, Tom, Jerry, and Red, culminating in a confrontation in St. Paul’s Cathedral where the cats hide in the organ.

The cats escape from the cathedral, Kidnap Red, and lead Holmes and the others to a graveyard where they find the stolen diamond. The mysterious horseman arrives first, but Jerry secretly steals a key, hinting at further plans to uncover the culprit.

The team discovers that the professor, who captured Red, is actually Moriarty, planning to use the diamonds as part of a heat ray device to destroy the Tower of London and steal the Crown Jewels. Moriarty’s plan involves manipulating sunlight during an upcoming eclipse.

Moriarty advances to the Tower of London with the stolen jewels, using his heat ray to slice through its walls. Tom, Jerry, and Red attempt to stop him, aided by Spike, Tyke, and the cats, leading to a dramatic chase and battle atop the Tower Bridge.

Holmes and Watson arrive just as Moriarty activates his device, and Holmes fights Moriarty atop the carriage on Tower Bridge. Moriarty is arrested along with the cats, with Droopy securing the reward. The villains are defeated, ending their sinister plans.

Red ends up marrying a wolf, and they begin howling before running off, adding a comedic ending. Meanwhile, Jerry secretly sets Tom’s tail on fire, leading to a final chase. Droopy is revealed to be responsible for the wedding, closing the story with humorous notes.