Well, Riley Sager, you’ve done it again. You’ve crafted the perfect thriller, equal parts mystery and horror, a propulsive page-turner.

Lock Every Door is told from the perspective of Jules, a young, broke victim of chance. After losing her job and catching her boyfriend cheating, she finds herself homeless and without many options when she discovers the perfect job. The iconic Bartholomew, a historic apartment building overlooking Central Park, is looking for apartment sitters. Jules thinks she’s won the lottery, but nothing at the Bartholomew is as it seems. Soon after moving in, another apartment sitter mysteriously disappears, and Jules begins to suspect there is a sinister explanation.

Sager does an amazing job of sharply juxtaposing opulence and desperation. The glamour of The Bartholomew is seen through the eyes of someone severely in debt who lives paycheck to paycheck. Loneliness and isolation are also a major themes. Jules is very isolated in her life, having lost both parents years earlier, as well as a sister who mysteriously vanished when Jules was a teenager.

I read Lock Every Door over the course of one night, staying up well past my bedtime, glued to the page. I would not recommend that approach. This is strictly a read with the lights on book, especially the last few chapters. It was nearly impossible for me to sleep after I finished this book, both because I was terrified, and because I was blown away by the complex story of Lock Every Door. This is definitely not one to miss, but you have been warned, keep the lights on.