When they hear about a competition to find the world's worst mother, Bruno and Sophie and Emily are all delighted to volunteer their annoying mothers. Their mothers duly disappear and are replaced by ideal 'Aunt Annas', who cook only the kids' favourite foods and never make them do their homework or tidy their rooms. But the children soon discover that there is something sinister about these 'Aunt Annas', and they set out to rescue their real mums from the clutches of a crazy toymaker on a remote island. A fishy tale of betrayal, intrigue and adventure on the high seas—and the dog gets shot!