Colin the Crab is a hard worker who loves spending his spare time with friends. He has a charming home, but lately it has started to feel a bit empty and lonely. Is it time for Colin to find a spouse? Colin is confused, and none of his friends knows how to advise him.

One day Finley the Frog, the director of the river museum, calls Colin for help when an accident befalls an important exhibition of shells and corals. Among the broken shelves, Colin makes a delightful discovery: a girl crab with the most beautiful eyes along the riverbank.