Cat has been forced into an arranged marriage with William - a situation that comes with far more strings than even she could have anticipated, especially when she learns of his family's intentions for them both. Meanwhile, Max and the gargoyle investigate The Agency - a mysterious organisation that appears to play by its own rules - and none of them favourable to Society. Over in Mundanus, Sam has discovered something very peculiar about his wife's employer - something that could herald a change for everyone in both sides of the Split Worlds.