The otterly bonkers Brown family are hugely excited, as today's the day they move to their new home. But when they get there they find the beastly Black family have got there first. This riverbank ain't big enough for the both of them, so there's only one thing for war. Well, not real war. Otters are more into playing than fighting, so instead they decide to hold a giant sports day - and may the best otters win.

There’s a new family on the river… the beavers. And they’re ruining everything for the Otters. The beavers’ big fat dam has blocked up the river and worse… it’s stopped their supply of delicious crayfish! Something must be done! It seems like things can’t get any worse for our otters until they discover a mountain lion has also moved in. Can the riverside families overcome their differences to scare off this hungry-looking foe?