Frozen in Time by Ali Sparkes
1956 Freddy and Polly are used to helping their father with his experiments. So they don't mind being put into cryonic suspension - having their hearts frozen until their father wakes them up again. They know it will only be for an hour or two, so there's nothing to worry about . . . Present Day Ben and Rachel have resigned themselves to a long, boring summer. Then they find a hidden underground vault in the garden containing two frozen figures, a boy and a girl. And when Rachel accidentally presses a button, something unbelievable happens . . . Can Polly and Freddy adapt to the twenty-first century? Will their bodies survive having been in suspension for so long? And most important of all, what happened to their father - and why did he leave them frozen in time?