Flight of the Silver Turtle

Sam is back in Edinburgh with his brilliant uncle, inventor Professor Ampersand, and cousins Zara, Ben and friend Marcia. Their efforts to build an experimental flying boat leads to a dramatic discovery - a long-lost secret invention that holds the key to anti-gravity. But a ruthless and sinister organisation will do anything to own the machine and Sam and his friends must stop them at all costs . . . So begins an adventure of nocturnal museum thefts, encrypted clues, murder cover-ups, mysterious airships and sky-chases over the rooftops of Edinburgh.