** Contains Spoilers **At some point in the future, humanity is wiped out from the surface of the globe and forced underground. Society splits into three factions, the elite Sun realm, the working drones of the Moon Dwellers and the underclass of the Star realm.Adele Rose is in prison for no reason other than her parents were branded as 'traitors to society'. Her family torn away from her, she waits to rot in prison. Tristan Nailin, son of the Sun Realm president, is a prisoner too...a prisoner of his fathers empire and expectations.When he drives by the prison where Adele is a 'guest', they find themselves powerfully physically and psychically affected by their encounter, even though they don't meet. That night, both Adele and Tristan break out of their lives and go on the run. Adele to find her sister and parents, and Tristan to find what spell Adele has cast over him.David Estes has written a technically flawless book. The characters are all fleshed out, the dialogue sharp and witty, the chapters all end on cliffhangers that keep you glued to the page. The plot bounces along and doesn't lag. The world he creates is consistent and logical. I did spot a few errors with a few things...being electrocuted on barbed wire fence would make you clutch it tighter, not throw you off, and would humanity a thousand years underground know what cardboard was? But those are minor points.So why don't I want to give it five stars?For me, the characters didn't gel. I never connected with them in any meaningful way until close to the end. I had a feeling that I'd seen them all before a dozen times: Feisty yet vulnerable female heroine. Handsome yet insecure male hero. Minor characters for some comic relief and tension, one of who dies.When Cole is killed near the end of the story, I should have been moved. I should have felt chills when soldiers footsteps echo from the next stone corridor. I think what was missing for me was atmosphere. I should have smelt the damp air of the caves and the chill breeze as it moved around me. I didn't get a feeling past a physical description of how different the sun realm was from the moon dwellers, for instance. It took me twenty or thirty percent of the book to realise the light was lower in the moon caves.I also felt that towards the middle of the book, Estes suddenly realises he has a sequel in mind. Thus, characters suddenly start talking about 'The Secret', and there is no explanation for Adele and Tristan's odd psychic bond.Adele's father talks only in elliptical sentences for the few pages he's in the book, then is quickly pushed out again, taking Adele's sister with him. Two plot points tied up in one swoop. The same with the super killer Rivet, who is quickly dispatched...so much for being a super killer.Ultimately though, despite the excellent writing, pacing and characters, everything about the book felt like I had seen it before, and towards the end it started to feel like a setup for the sequel.