frozen within time

1956
Karl and holly have always known their father is a genius.
so they've never minded helping him with his experiments. even when that means being put into cryonic suspention----having their hearts frozen until their father wakes then up again. they know it will only be for an hour or two, so there's nothing to worry about . . . .

2009
Alex and Kristen have resigned themselves to a long, boring summer. then they find the hidden underground vault in the garden----and inside it was two frozen figures, a boy and a girl. And as if that isn't spooky enough, when Kristen accidentally presses a button, something unbelievable happens . . . .

can holly and Karl adapt to the twenty first century?
Will their bodies survive having been in suspention for so long?
And most important of all, what happened to their father----and why did he leave them frozen within time?