It is the summer of 2013 and Abigail Kamara has been left to her own devices. This might be considered a mistake. While her cousin, police constable and apprentice wizard Peter Grant, is off in the sticks, chasing unicorns, Abigail is chasing her own mystery. Teenagers around Hampstead Heath have been going missing but before the police can get fully engaged, the teens return home - unharmed but vague about where they've been. A new novella in the "Rivers of London" series.