With the Second World War looming, four young people sit on a train waiting to be evacuated to a safer place…but they don’t want to go. They climb out of the carriage and head back home to Greenwich, forming an unlikely friendship.

They spend their days trying to be useful. Laurence is building a secret machine. Gemmy searches bombed-out homes for things of value – only to find an adorable mutt she can’t even give away.

Franklin wants to join the Fire Service, although it means lying about his age. Olive looks after her father, who is broken by the deaths of his fellow firefighters. And together, the four roam the streets of London, discovering their resilience amongst the secrets of the city.

But as the Blitz unleashes a barrage of bombs on London, turning the sky ragged with flame, can the friends keep each other safe and survive?