Archie loves his little sister very much. But he doesn't always understand Olive's strange behaviour - sometimes, Archie is convinced that Olive is an alien from outer space! The follow-up title to the much-loved Olive Marshmallow, which introduces Archie and his brand new baby sister Olive. The perfect picture book for any child and parent navigating the relationship between siblings. A sweet and humorous story that all families will relate to, beautifully illustrated by Katie Saunders.