<p>Sam and Luke vanish: there one second, gone the next. That&rsquo;s the last thing Kitty Strange expected to happen while in her lounge after school with her best friend Lizzie, Luke&rsquo;s twin sister, and Toby, Kitty&rsquo;s twin brother. Where have her younger sister and Luke disappeared to?</p><p>Minutes later, Kitty, Toby, and Lizzie materialize in a parallel world, with just one clue as to where Sam and Luke are. What do they do next?</p><p>Launch a rescue mission, of course, that leads them to an academy for gifted children owned by Dr Ravenel Raven, an Aquaterran computing genius. Using a &lsquo;jumping machine&rsquo; he stole from mysterious aliens, Dr Raven plans to visit parallel universes in search of a cure for his sister&rsquo;s incurable illness. But first he needs to get the machine working properly &ndash; at any cost.</p><p>Kitty, Toby, and Lizzie learn that in the first experiments humans have indeed been &lsquo;jumped&rsquo; to Aquaterra but are having memory problems. And what&rsquo;s worse, in an attempt to repair their memories, they&rsquo;ll soon be jumped to Earth and back, which in fact may well scramble their memories beyond repair.</p><p>The countdown to save Sam and Luke begins &ndash; but in a hi-tech alien world where real and virtual are sometimes impossible to distinguish, with armed sentinels chasing them, and with the jumping machine to find, will they be in time?</p><p>A fast-paced and thrilling sci-fi adventure for middle-grade readers.</p>