The Alien Detective Agency series of reading books, featuring Jack Swift and Wanda Darkstar, are for children and young adults aged 8 to 14 and over who are struggling to read. Each book has been carefully written for those with a reading age of approximately 7 to 8, but are packed full of adventure and brilliant illustrations to really grab the reader interest.Comet Riders - The Icylons, an alien race of intelligent snowmen, want to turn our planet into a frozen world so they can live on it. They plan to crash a comet into the Earth to create a new ice age. Jack and Wanda must stop them... but how?