Penelope Crumb has a brother so awful he must be an alien, a mum who draws body parts and a missing grandpa, nobody in the family has seen him since Penelope's father died. So Penelope and her friend Lizzie Maple set off across town to find Grandpa Felix, skipping school, taking trains and calling every F. Crumb in the phonebook. But what is Grandpa Felix doesn't want to be found?