Suddenly they have to learn to fend for themselves: find food, find somewhere to sleep - essentially, learn to stay alive. And I know what you're thinking... how could two 12-year-old London kids possibly survive such a calamity? Well, luckily for them, they had re-appeared in the exact same spot they vanished from: a tiny attic laboratory in a rambling old Elizabethan house on Puddle Street.

It's where Toby's uncle, professor Arthur C Sprocket, believes he has invented an Anti-Gravity machine. Toby and Sally are massively impressed when they first see the machine - even more so when the professor asks them to be his test pilots. Turns out though, it's not an Anti-Gravity machine.

It is in fact a fully-operational time machine - a terrifying situation Toby and Sally discover when it disappears from No. 2 Puddle Street in a shrieking spluff of blue smoke.