Last October, Alice Ogilvie's ex-best friend, Brooke Donovan, was killed - and if it weren't for Alice's unlikely alliance with Iris Adams, and the complete works of Agatha Christie, the wrong person would almost certainly be sitting in prison for the crime. The Castle Cove police aren't exactly great at solving crimes.

Which is why, on the night of Castle Cove High's annual dance, Alice decides to explore Levy Castle - the site of one of Castle Cove's most infamous deaths. The classic film star Mona Moody died there almost a century ago, and Alice is pretty sure the police got that investigation wrong, too. But before she can dig deeper, she walks right into the scene of a new crime: Rebecca Kennedy, on the ground in a pool of blood. And another of Alice's ex-friends - Helen Park - standing over her.

The Castle Cove Police Department thinks it's an open-and-shut case, but Alice and Iris know that to understand the present, sometimes you need to look to the past.

Castle Cove is full of secrets, and Alice and Iris are about to uncover one of its biggest - and most dangerous - secrets of all.