The Icicle Illuminarium — N.J. Gemmell

Kick, Bert, Scruff, and Pin are rejoicing -- their dad has been found! But he's ill from his wartime experiences, and he's sent away to recover. Could their mother still be alive, too? The four siblings begin a wild goose chase to search for clues. But it all goes horribly wrong when they're kidnapped and imprisoned in the coldest, loneliest, and most falling-down mansion in England. Luckily, there might be a secret friend or two to be found in this odd place.