Joe is upset to learn that his mum and her horrible boyfriend Dean are going on holiday to Spain for a week, leaving Joe behind on his own. Relief comes when he meets Asha, who is also feeling abandoned. She's had a fight with her mum and has, run away to live with her grandad. After an attempt to fix the toilet, Joe discovers a package, left there by dodgy Dean. It's full of £20 notes, and it's got to be illegal!
Asha persuades Joe to go on a bus ride around London with her and Otis. For the first time in ages, Joe feels free. They have a fun day out and Joe decides it's time to tell Asha the truth - that his mum has been away all week but she's coming home soon. But when that day arrives, Joe's mum doesn't come home, and Joe starts to worry about her safety.
Joe gets ready for school but he looks a sorry sight. His mum should have been home three days ago, he's run out of money and is almost out of food. His fear of Dean still stops Joe from touching a penny of the money he found. At break time, Joe's nemesis, the bully Perry Fletcher, turns the screws on Joe a little tighter by demanding money - a pound today, two pounds tomorrow. Back at home a starving Joe eats the out-of-date curry that Dean left in the fridge, which has disastrous results and he is violently sick for two days. He can't go to school, hallucinates that Dean is in the flat, and then the electricity runs out. Can things get any worse for Joe?
Alone again, Joe loads the cash into his backpack, along with a few clothes, in preparation for running away early the next morning. Late that night, the threatening man (known as the Watcher) turns up demanding his money and tries to kick down Joe's door, but Joe is saved by his neighbour Kosmy. Early the next morning Joe leaves for Paddington Station and is unexpectedly joined by Asha. They don't see that they have been followed by the the Watcher, and this time he's not alone.