Based on the book, Basil of Baker Street, this is a very good Disney movie (which makes me suspect I might have reviewed it before, but anyway ... I've seen all the Disney toon movies now, so doesn't hurt to highlight it again).
Basil lives under Sherlock Holmes house and does the same brilliant detective work. A little girl goes to him to find her kidnapped father and he uncovers a plot that Professor Rattigan has masterminded to take over Mousedom. Very entertaining and as action-packed as any Holmes movie.:)