Silence!

The Silent Patient, by Alex Michaelides, is one of those smoothly written thrillers that hypnotizes you with the easy reading so that you don't think about the absurdity of some of the plot devices (like a diary that contains every piece of dialogue and information to uncover the killer . . . a diary written until moments before death) and I will stay silent about everything else, except that there is--of course-- a twist (which you might see coming if you're thinking deeply about the plot, but the best way to read these things is a mile-a-minute while biking at the gym, so that everything is a surprise).