The Full Flight series of reading books 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.Invaders - Mark discovers a strange creature. When he takes it home, hundreds of them start to appear. He knows he must discover what these creatures are, before it's too late.