In Rachele Alpine’s A Void the Size of the World, protagonist Rhylee has several problems. The first is that her sister, Abby, has disappeared. The second is that Abby disappeared because she caught Rhylee kissing Tommy — who’s Abby’s boyfriend. The third is that Rhylee likes Tommy, but the police strongly suspect that he might have had something to do with Abby’s disappearance. What’s a girl to do when her love interest might be the person who hurt her sister?

Rhylee isn’t the first protagonist to deal with the age-old question — what if the person I like is guilty of something horrible? It’s a particularly common question in mysteries, where anything is possible and anyone could be lying. It’s also fascinating because, as pretty much everyone learns at some point, you can’t just turn your feelings off, even if you wish you could. After I finished A Void the Size of the World, I started thinking about other stories that have love interests who might not be as innocent as they seem. Here are some of my favorite books that keep you guessing until the very end.

I tried not to blow any big twist endings, but this post does have minor plot spoilers for all of the mentioned books. You have been warned!