His body of work includes modifications of classic pulp fiction novels. The covers for these books often show a lot of exciting action that would appeal to the young men who read them. But by physically separating the illustrations from the books themselves, they appear to be even more mobile. The visual effect packs quite a punch.
Furthermore, as a photographer, Allen knows how to use distance and spacing to tell a story with a scene. You could easily tell a complete story from just the look that these two people share and the other two ladies don't.
You can view more of Allen's work on Instagram.