Frog and his friends, the duck family and the water vole family, live happily beside the river until Beaver arrives, eager to make his first dam the biggest and best ever. As it nears completion, the water sinks very low along the neighbors' riverbank. Frog explains the problem to Beaver, who doesn't listen well but finally suggests that the animals move upstream. Grumbling, they do, but soon the dam bursts, destroying their new homes, and Beaver almost drowns. Grateful to Frog for saving his life, he restores the animals' old homes and scales down his dam project. While adults may superimpose messages related to ecological conservation, city planning, and so on, children will simply enjoy the story of an eager but thoughtless young fellow who learns how to be a good neighbor. James creates a simple, effective narrative for reading aloud, but the large, ink-and-watercolor artwork brings it to life, illustrating the increasing chaos of the formerly peaceful setting as well as the characters' emotions as events unfold. A pleasing picture book.

New-to-the-river Beaver is oblivious that his newly constructed dam ("the best dam for miles around...Everyone will love it") negatively affects the animal families living downstream. Frog tries to troubleshoot the cohabitants' dilemma until eventually the dam bursts and Beaver needs their help. James's expressive pen and watercolor illustrations help convey the moral that even well-intended actions can hurt others.