Josh and Danny can't believe their luck when crazy scientist, Petty Potts, turns up on the same beach as them. It's the perfect chance to 'borrow' her new spray that SWITCHes humans into turtles. Soon the boys are having a great time, diving through the waves and slurping on jelly fish . . . Until they swim into serious danger.

Josh and Danny are on holiday with their parents in Cornwall-so the last person they expect to see is mad scientist, and next door neighbour, Petty Potts! So when the twins see her on the beach - holding a turtle under each arm-they can't help but wonder what she's up to. The thing is, the boys have got other things on their mind. They've found another mystery marble clue, and need to get out to the ruined fort on the rocky island. But they take too long and the tide

comes in, trapping them. Luckily, they have a bottle filled with SWITCH spray and turn themselves into leatherback turtles! Their swim back to mainland is filled with danger . . . Will Danny be able to save Josh from the fishing net before he SWITCHes back in to a boy?

Praise for SWITCH

This book has helped my son, 5, move on from picture books at bed time to one with more words. An excellent choice for reluctant readers who will be thrilled at the idea of turning into a bug, mad inventors and lots of adventures.

The book is great fun and involves the reader, who really feels as though they are part of the story. Along the way the reader learns a surprising amount about pond life.

Praise for Ali Sparkes's Frozen in Time, winner of the Blue Peter Book of the Year Award

'I know now what they mean by a plot that is toe-curlingly good . . . brilliantly inventive and rollicking fantastical adventure'

'Frozen in Time shows [Ali's] skill at fusing traditional children's storytelling with modern tales . . . Sparkes's sci-fi conspiracy thrills will keep 21st-century kids transfixed'

'It was outstanding. It blew me away'