It's the holidays again, and once more the children are off to stay with Miss Pepper while Mr and Mrs Lynton set off to America for a few weeks. They've timed their own holiday just right so they won't have to spend time with their pesky son Roger, and their irritating daughter Diana, and their dreaded nephew Snubby—or at least that's how it seems to this reader, who finds it hard to imagine why parents should want to go off somewhere just when their children arrive home from boarding school. How inconsiderate! But away to America they go, leaving the children once more in the capable hands of Miss Pepper, who is to take them all off to Rubadub, a delightful place she frequented in her younger days.
Rubadub is truly an exciting place for the children, an old-fashioned seaside village with a pier, a promenade, a sandy beach... and a Secret Harbour where new submarines are tried and tested! Not only that, but there's Rubadub Pool, a dangerous whirlpool nestled between rocks that sucks everything down to its watery depths. And there's a blowhole too, where water surges through an underground passage and blows out the other side. It all sounds too exciting for words!