Basil of Baker Street - mouse detective genius - is off on a perilous expedition leading thirty-two mice up a towering mountain. Their objective: to locate and rescue a famous colony of mice - missing for centuries! A clue in the form of an arrow with strange markings has sent Basil scurrying off to Switzerland in search of the lost colony. But all is not smooth in the path of our Sherlock Holmes of the Mouse World. He must confront the mysterious giant snow mouse, and the sinister plots of evil Professor Ratigan, ruler of the mouse underworld!