This isn't just a puzzle. It's a lethal game of survive or die ...

Estranged twins Mabel and Kai each receive an unexpected invitation to stay for a week at their grandfather's Parisian chateau. Neither remember meeting their grandfather, and neither had any idea that he was still alive.

The author of a notoriously difficult puzzle book, their grandfather is bed bound and dying. His last wish? For Mabel and Kai to solve it. The prize: unimaginable riches. The catch? They are trapped in the house until one of them wins ... or dies trying.

Their only other hope for escape is a mysterious student who has been working for their grandfather and seems to have eyes for both twins. But the walls are closing in and the contest takes darker and darker turns towards the supernatural. In this deadly game, there can only be one winner.

Perfect for fans of The Inheritance Games and Wednesday.