Cell

In Cell, a mysterious signal spreads through the mobile phone network and turns most people into violent, mindless versions of themselves. An artist is caught in the middle of it, trying to get back to his young son. That is the whole set-up you need. Suddenly, the little device everyone carries looks like a spectacularly bad idea.

For me, the frightening bit is how quickly something ordinary becomes a threat. There is the immediate fear of other people, of course, but the search for his son gives it a more personal ache. It is hard to think about danger in the abstract when someone you love is out there somewhere. I would put this at a four for scares: the premise is nasty, the violence is part of it, and the worry does not politely wait its turn.

This is one for a dark night when you want your horror to feel close to the everyday, even as the situation grows enormous. Make a strong coffee, get comfortable, and consider giving your phone a suspicious look. It probably deserves one. If you like a frightening set-up with a clear human reason to keep turning pages, this belongs on your reading list.