Best friends Tilda, Kiara, Ruby and Ginny are all members of the Brighthawks – a global outward-bound association for girls – and their troop are hosting this year's annual summer camp. They're thrilled to welcome other Brighthawk troops from around the world… but they are about to discover that some attendees have come from much, much further afield! Who are these aliens? What do they want? And will our Girl Troop earn their "Planet Protector" badge.