The Piper commands an army of vicious dogs to rid the burgeoning village of mutant rats, and when shortchanged uses the dogs to herd the children on a march to his slave ship, after leaving the village in flames.
Only 5 mounted rescuers can be spared from firefighting.
3 are eliminated in an ambush, leaving a widower trying to save his estranged son, and the village's sharpshooter midwife trying to save them all.
The story is told through the eyes of a father and son. The boy is struggling to manhood while they both suffer the pangs of their wife/mother's suicide years earlier.
The unusual behaviour of the rats is explained in the end by a disturbing revelation.