How does the word "battlefield" relate to the theme of the book?
Thanks.

Battlefield is the name of the town where the abductions take place.

Hi! i like the idea of the white locked room, but about the blood, how scary the cover should look? just some drops here and there, a lot of blood like after a massacre, just a stain on a wall or what? :)
About the puzzle element, some kind of strange looking locking system for the door would be ok?
Thanks!

The book isn't horror or torture-porn, so buckets of blood like after a massacre won't work. We're trying more for "there is some threat where someone can get hurt", rather than "everyone will die". A stain or drops would work.

A strange locking system would be great!

Thinking about this today, another design that could work would be a close up in the foreground of a syringe lying on the floor at an angle, perhaps with blood or another liquid dripping out. Then, in the background, an open door with the feet and legs of a teenager girl being dragged out. Depending on how stylized it is, it could also have "foot furrows" showing where her feet dragged on the ground. The initial point of focus would be the syringe, with the viewer only later realizing that someone was being dragged away.