Basil, détective privé

London, 1897. One night, Doctor Dawson discovers the little Olivia in tears on his way. Daughter of the toy maker Flaversham, she tells him that her father has been kidnapped and that she is looking for the house of Basil, a brilliant detective. The latter has taken up residence in the basement of 10 Baker Street, in the home of the famous Sherlock Holmes. Olivia confides to him that it was a bat that kidnapped her father. For Basil, there is no doubt that Ratigan, the most diabolical rat in the kingdom, is behind all this...