Fievel plays with his friend Jack's boomerang, which lands near Cat R.Waul's bad cats and Chula the Tarantula in a barn; there he overhears they have plans by the river. So Fievel makes an appointment with his feline simpleton friend Tiger to get the boomerang back, but his parents only allow him to go to the river -ignoring why- if he takes his stupid sisters along. As if that weren't troublesome enough, there's a hungry cougar around and the boomerang accidentally awakes a nest of rattle-snakes. When they're all late, papa and ma Mousekiwitz go looking for their offspring, but don't arrive till Fievel has found a clever way out of all their trouble...
—KGF Vissers