A brilliant high-concept debut thriller - just how do you solve a murder when you only remember yesterday?

'The thriller of the summer' - Observer

'Yap is a phenomenon' - Guardian

'The intrigue of Gone Girl and the drama of Before I Go to Sleep' - iNews

'So hotly tipped it should come with scorch marks... Quite literally mind-bending' - Red

Today, the police are at your door.

They say that the body of your husband's mistress has been found in the River Cam. They think your husband killed her two days ago.

You can't recall what he did that day, because you only remember yesterday.

You rely on your diary to tell you where you've been, who you love and what you've done.

So, can you trust the police?

Can you trust your husband?

Can you trust yourself?