From London, Penny Hawthorne, age ten, and brother John, one year older, travel to Plainsbury to spend a vacation with their grandfather. The sunny country-side seems dull to these two who would rather rummage about in a grimy, cobweb cluttered attic. A crystal ball is discovered; a talking gold dolphin appears and advises them to search for the Greater Gold Dolphin. They are given the power to choose any year in history and turn back the clock to various eras. The rigid dialogue of the flimsy cardboard children seems to have been lifted from one of their Grandfather's dusty primers. The concoction is heavy with fantasy and hazy on reality. The story is pointless and unconvincing.