What I liked about this book is that the aliens are interesting and different. Ok, of course, they are different but these have some unique features and characteristics plus they need humans to continue living. Good descriptions make it even more interesting. Gravity by Melissa West is a Taking Novel which refers to Ancients (aliens) taking from humans the substance they need to live. Humans are required to wear a sleeping mask during this process and must not peek.
Ari, the heroine is especially talented in warfare and trained in Special Ops by her father. As an alien spy Jackson wants to learn all he can from her and other humans. At the same time Ari and Jackson are trying to prevent a war between the Ancients and humans. Ari will do what she can even if she must betray her father. The planet Loge needs the earth and its people.
I am looking forward to the second book Hover and answers to many questions that came to mind.