When Gustavus Pulvertoft finds himself saddled with a horse with the power of human speech, he little imagines how quickly he will come a cropper. His courtship of the horse-loving Diana Chetwynd goes swimmingly so long as his talking horse is on good terms with Miss Chetwynd's grey mare... but when their trusty mounts fall out, a series of terrible events ensues which Pulvertoft is powerless to prevent. His determination to get revenge on the horse leads to his ultimate downfall.