The Great Emperor Detective

In London 1897, a young Scottish-Welsh mouse named Apple Bloom is celebrating her birthday with her toymaker sister, Applejack who gifts her with a beautiful ballerina doll. Suddenly, werid looking men named Aldryx and A.G.O.T.I , one has red skin and one has black skin, bursts into the Apple Family' Barn, and after a short struggle disappears with Applejack. A frightened Apple Bloom comes out of hiding and calls out into the night for him.

Apple Bloom searches to find EmperorDaFirst of Baker Street, a world-famous detective. Kapi, who has returned from a gaming computation, stumbles upon Apple Bloom and helps her find EmperorDaFirst's residence. At first EmperorDaFirst is reluctant (because at first he thinks that she is lost), but when Apple Bloom mentions the red-skinned and black-skinned men that kidnapped her father, EmperorDaFirst reveals that the men's names is Aldryx and A.G.O.T.I and is a minions of the evil Professor Solazar, an evil genius whom EmperorDaFirst has been trying to capture for years. As it turns out, Solazar has kidnapped Applejack to create a clockwork robot which mimics the Queen of the Mice so Solazar can rule England. Applejack initially refuses to participate in Solazar's scheme, whereupon Solazar orders Aldryx (Not A.G.O.T.I) to capture Apple Bloom. If Applejack refuses to comply, Solazar will feed Applejack to his pet cat, Lucky Cat (he breaks the ballet doll by squeezing it for emphasis). Solazar and his minions celebrate his new plan, but unfortunately one of his minions, Pico, accidentally (albeit drunkenly) calls Solazar a ice and is promptly eaten by Lucky Cat (But Pico survives somehow) , and Solazar demands they continue singing.

EmperorDaFirst and Kapi then use Sherlock Holmes' pet, a Basset Hound named Funyun, to track Aldryx's scent to a nearby toy store. Aldryx is surprised by EmperorDaFirst, Kapi, and Apple Bloom in the toyshop where he is stealing clockwork mechanisms and toy soldiers' uniforms for Solazar's plan. He hides and later traps Apple Bloom by ambushing her from inside a toy cradle. EmperorDaFirst and Kapi pursue Aldryx but become entangled in some toys and fall behind, giving Aldryx enough time to escape with all the materials he needs and Apple Bloom.

While upset with Kapi for not watching Apple Bloom, EmperorDaFirst is certain they'll find her. As they are searching the shop, Kapi discovers Aldryx's forgotten checklist, which details everything Aldryx has taken with him. Solazar brings Apple Bloom to her sister, but their reunion is short-lived as Solazar orders Applejack to finish the robot, or harm will come to Apple Bloom. When Aldryx finds the list missing, he tells the Professor that EmperorDaFirst followed him. The Professor angrily feeds Aldryx to his cat, but after realizing that EmperorDaFirst will be coming for Apple Bloom, he plans to trap EmperorDaFirst with a lure. Back at Baker Street, EmperorDaFirst discovers through close examination and some chemical tests that the list came from a riverfront, and he and Kapi look for a small tavern near the Thames where the sewer would connect to the river. EmperorDaFirst and Kapi disguise themselves as sailors and enter the tavern, inquiring for Solazar. As they wait, Aldryx enters the pub. They follow Aldryx through some pipes to Solazar's headquarters, only to discover that Solazar and his henchmen had prepared for their arrival. Triumphant, Solazar ties them to a spring-loaded mousetrap, connected with a Rube Goldberg machine constituting a gun, a crossbow, an axe, and an anvil with a record being the timer stated by Solazar that when the song ends, the trap starts. Solazar sets out for Buckingham Palace, where Aldryx and his accomplices defeat Royal Guard and kidnap the Queen. EmperorDaFirst briefly despairs at being outwitted but snaps out of it just in time to deduce the trap's weakness and escape.

Back at Buckingham Palace, Solazar forces Applejack to operate the toy Queen while his men pose as Royal Guards, and the real Queen is taken by Aldryx to be fed to Lucky Cat. The fake Queen declares Solazar ruler of all Mousedom, and, after thanking his robotic consort, he announces his tyrannical plans for his new "subjects", including several unfair taxes. Just then, EmperorDaFirst, Kapi, and Apple Bloom save Applejack and the real Queen and apprehend Aldryx along with Solazar's other two henchmen (Selver and Israelball). EmperorDaFirst then seizes control of the mechanical mouse-queen, forcing it to denounce Solazar as an impostor and tyrant, all while breaking into pieces. The crowd, enraged by Solazar's treason, start climbing onto him and defeating his shanty guards. Solazar frees himself and escapes on his dirigible with Aldryx, and holds Apple Bloom hostage.

EmperorDaFirst, Kapi, and Applejack create their own craft with a matchbox and some small helium-filled balloons, held under the Union Jack. A high-speed chase above the city ensues. Solazar throws Aldryx (who can't fly) into the Thames River below to "lighten the load", and then attempts to drive the dirigible himself. EmperorDaFirst jumps on to the dirigible to confront his nemesis; however, without a helmsman, Solazar is unable to steer the craft, and ends up crashing straight into Big Ben. Inside the clock, Solazar and EmperorDaFirst l face off in a final battle. EmperorDaFirst manages to gets Solazar’s coat tangled in the clocks gears. Seeing Basil escaping, Solazar completely loses his mind and goes insane. EmperorDaFirst rescues Apple Bloom and safely delivers her to Applejack, who is still on the balloon with Kapi. He plunges into EmperorDaFirst, and they both fall onto the clock's hour hand. The fight ensues, and Solazar begins to viciously thrash EmperorDaFirst. It seems as if EmperorDaFirst's luck is about to run out until the bell tolls and Solazar plunges off the hand taking EmperorDaFirst with him. However, while Solazar fell to his presumed death, EmperorDaFirst saves himself just in time with the motor of Solazar's destroyed dirigible.

Back at Baker Street, EmperorDaFirst and Kapi recount their adventures as well as the queen's gratitude for their saving her life, and afterward, the Apple Family leave. Kapi figures it's time for him to leave as well, but the scene is interrupted by a distraught new client. EmperorDaFirst then persuades Kapi to remain as "my trusty associate, Gamer Kapi, with whom I do all my cases".