Basil Holmesington Of Baker Street was born to Eugene Holmesington (a mouse detective) and Abigail Holmesington (a mousewife) in Lower 221B Baker Street in London, England, one Januay 6. He was the youngest of 6 children; his five siblings were Marcus, Belladonna, Shelldon, Beverly, and Elizabella. As a baby, Basil was very precocious. He could talk, walk, count, sing, speak other languages, play musical instruments, and do complex math before he reached preschool age. In fact, the enfant prodigee was constantly babied by his parents and often picked on by his elder siblings.

Basil continued to live in “the house on Baker Street”, until he went to college at Oxford as a pre-teenager (he had skipped many grades in school). After a couple years of easy studying and hard work, a teenage Basil finally graduated from Oxford with a degree in law enforcement and detection (but not without meeting a few friends like Cyril The Pigeon and Evian Anderson).

In 1882, Basil moved back to London, and continued to live with his parents at Baker Street, while his siblings moved out to live their own lives. It was that same year, that Basil, with the help of his father, Monsieur Victor Claudius, and the great Sherlock Holmes, officially became The Great Mouse Detective.

As the years went by, Basil came across many scoundrels, like Jaywalk James, Adrienne Ratburn, and the “Flashy Farrell Brothers”, to name just a few. As a young adult, Basil was determined to find out the cause of a huge crime wave that had recently surged. In very little time, he realized that all the criminals and villains in the world were being sent to destroy London by “the nefarious Mouses Fiennes”, his worst archenemy.

It was in fall of that year, that Basil, during a huge Guy Fawkes Night festival, stumbled across the beautiful Gypsy dancer Esperanza, as well as a young Professor Ratigan. Basil and Esperanza gradually fell in love with each other, while a maturing Ratigan was left in the shadows. As he became an adult, Basil and Esperanza were about to get married in St. Paul’s Cathedral, but Ratigan killed Esperanza before the two mice could be wed. Basil, crushed by the death of his first love, solemnly swore to himself that he would not rest until Esperanza was avenged. It was then, and only then, that Ratigan officially became Basil’s biggest enemy.

Basil continued to work as a detective, but he had changed greatly since that terrible year. He became cold, emotionless, and somewhat cruel, even heartless-sounding. And that wasn’t all that was different about him: he had refused to catch any criminals except for Ratigan himself.

But that would all change soon enough...

Basil’s greatest challenge came in 1897, three long, hard years after the time Esperanza died. It was the year of Queen Mousetoria’s Diamond Jubilee, and every mouse in London was celebrating their gracious ruler’s 60th year as Mouse Queen Of England. Basil, however, was not interested in the festivities. He was intent on capturing Professor Ratigan.

But instead, his only client for the day was a little Scotsgirl, Olivia Flaversham. She had come to see him for help after her father, the kindly toymaker Hiram Flaversham, was kidnapped by a peg-legged bat. Basil refused to help the girl, until she mentioned Fidget. It was then that Basil would go on his greatest case ever...

As it turned out, Ratigan, now a young adult, was celebrating the Diamond Jubilee, too, but for different reasons; the day of the glorious occasion was his birthday, and as a present, Mouses Fiennes, his guardian and criminal tutor, was going to make Ratigan become king of all mousedom. Naturally, Ratigan wanted the best for this event, so to help prepare his birthday present, the teenage rat rogue had Fidget, his “peg-legged lackey”, to kidnap Olivia’s father in his toy shop that he worked in. Ironically, Hiram and Olivia were celebrating her birthday, too, which was coincidentally around the same time as Ratigan’s.

Ratigan was going to make his birthday wish come true by forcing the abducted Hiram to build a mechanical robot of Queen Mousetoria, which he would use to become Mouse King Of England (after he killed the Queen by feeding her to his giant pet cat, Felicia). Basil, Olivia, and Dr. David Q. Dawson (a retired army surgeon) were there to stop him. But it wasn’t easy...

Olivia, Dawson, and Basil had to go on a lengthy chase in a human’s toy store, during which Olivia got kidnapped by Fidget (who was doing a “shopping spree” of sorts for Ratigan’s "birthday present"/"diabolical scheme").

Then Basil and Dawson had to try and get Olivia back, but they had to disguise themselves as sailors, and go to the Rat Trap, “the seediest of riverfront pubs”, where they encountered “riverfront ne’er-do-wells”, sexy showgirls, bold barmaids, drugged drinks, and a very violent bar brawl.

Finally, Basil and Dawson finally reached Olivia, but were captured by Ratigan and his thugs, and were placed in a Rube Goldberg “overkill trap” that Ratigan (and Mouses, too) made to do the detective and his sidekick in. It took about 5 minutes for Basil to find a way to escape with his friends... and then, faster than you could say “Smile, everyone!”, they set off again.

Basil and the gang barely came just in time to save Queen Mousetoria, reunite Olivia and her father, destroy the “Mechanical Monarch”, and stop Ratigan’s evil scheme. But the “tortured soul” wasn’t finished yet...

After a lengthy race between Basil, Dawson, and Mr. Flaversham (in a hot-air balloon) and Ratigan and Fidget (holding a captive Olivia in their blimp) in the stormy London skies, Basil, Olivia, and Ratigan crashed into the clock tower of Big Ben. The three rodents had a dangerous chase inside the maze of Big Ben’s mechanical clockworks, which led to a fight between Basil and Ratigan on the clock's hands. Ratigan thought he would win, but Basil eventually tricked the rodent rogue into falling off the clock tower, falling into the Thames River. Basil finally joined his friends, and together, they flew back home, as Ratigan perished but Fidget emerged from the riverbank...

About a week later, Basil and Dr. Dawson had been knighted by Queen Mousetoria for their courageous deeds on that blessed Diamond Jubilee night. The Flavershams had been staying with Basil, Dawson, and Mrs. Judson all this time (because they had to recover from all that had recently happened), and they were now preparing to leave for a train to Scotland to visit their family for a while. Basil, Olivia, Dawson, and Hiram all said “goodbye” to each other, sharing their fond farewells. It was during the “Flaversham Case” (as it would come to be called later on), that Basil finally learned how to love and care for others again, now that his hope to avenge Esperanza had finally become a reality. The same night that the Flavershams left, Basil had gotten a new case, as the new-and-improved him: Lady Amelia Mousewell, the young baroness of the Hawaiian Territories, was missing a valuable ring that was a precious family heirloom, and she desperately needed to get it back. Basil took the case, but not without making Dr. Dawson his “trusted associate and partner”. After recovering the ring from Mouses Fiennes and his accomplice, Agent 001, Basil and Dawson continued to live together at Baker Street. But little did they know, that their lives would soon be changing again...

A few months after the Flaversham Case passed.

In the midst of the third month, another kidnapping had occurred. Crafty Fidget was behind it again, but this time, he had taken Franklin Frierson the very day he had returned from a traveling trip in Paris, under the orders of József G. Rathoug, the second cousin of Ratigan. A boy mouse under the name of Norman Frierson became desperate to find Basil after finding his name in a newspaper clipping to plead his case.

Thankfully, Hiram and Olivia, who had just returned to London from Scotland that night, came across the boy and took him to lower 221B Baker Street, and after formalities were complete, the case was also revealed to be intended to continue the legacy of Ratigan, and they were immediately prepared for the case.

Meanwhile, in Ratigan's former lair, Rathoug and a number of Ratigan's former thugs held a private funeral for Ratigan and prayed that his legacy wouldn't die out, ending with Rathoug promising to finish everything his cousin started.

Another month afterwards, Mouse London was taking a downfall. It was during the dawn of the New Mousetorian Age...

During the Month Of Change, Basil and Dawson hadn’t gotten many cases. But their luck changed when Basil successfully caught a jewel thief...unfortunately, Basil, “while chasing that notorious diamond thief”, had passed by the Flavershams’ toy shop... The Flavershams had been abandoned by their customers, and were just ever so near the brink of going out of business.

But Basil, thanks to Dr. Dawson and Mrs. Judson, was going to change that; he had decided to let the Flavershams move in with him. Them, eager to start a new life, couldn’t help but agree. And soon, Olivia, Arden, Hiram, and Olivia’s cousins, the flirty Timmy, the autistic Tina, the nitpicky Ursula, and the youngest twin Samantha were lodging in with Basil. Joining them were Norman, Kay, Scotty, Joanna, Alana, Kamaria and Rolf too, But Basil’s company didn’t stop there; in time, he married Queen Mousetoria’s long-lost twin sister, Victoria, and had a child with her: Fuschia.

After many adventures with his new Baker Street Family, Basil decided to continue being a detective, but he would not go on any cases if his family wasn’t there to support him. A year after the Baker Street Family formed, Basil and the gang were joined by 6 new members: the McBrides Julie, Jane, Eliza, Gadget, Sally, and Andrew), the traveling family who had adopted the baby Ratigan back then, before losing him to Mouses Fiennes. It was then, that the Baker Street Family was now truly complete.