If you didn't read the prequel, 'Snow White', a quick introduction:

It's superhumans vs. superhumans as Rayne and 15 try to escape the evil Lab that created them, Tristyn(16) and their other superhuman 'siblings', 11 and 12, in hot pursuit. Tristyn, who brought Rayne out of her normal, suburban-girl life in the first place, will do anything to help the girl he fell in love with stay safe, but 11 and 12 have one mission: to bring Rayne and 15 back 'home', whether they like it or not.

If you did read 'Snow White' or want to jump right into the story, Chapter 1:

Tristyn

He threw himself forward into the darkness, trusting his instincts to keep him going in the right direction- toward the road. 15 and Rayne needed a vehicle, and if the car he had abandoned days before was still there, that was their best option. He had to get there before they did, and before 11 and 12 got to them first.

Over the sound of the wind rushing past his ears he heard a crashing to his right and he turned toward it, focusing on the sounds of a fight on the other side of the hill. Someone cried out- Rayne- and his heart clenched in his chest, forcing him to even more dangerous speeds.

Then he was over the hill and crashing through the trees, where two shapes in white and two shapes in black fought like ghosts. 12, the bigger shape in black, was up against 15, both of the swaying back and forth as blows hit and were avoided. Rayne was against 11, her lack of training painfully obvious as she retreated, barely managing to fend off the worst of 11's blows. She didn't see him arrive, but 15 did, and he landed a solid kick to 12's stomach before launching himself at Tristyn.

The flying tackle caught him by surprise, and their combined momentum carried them up and sideways towards a tree. Both hit hard and 15's grip slackened, allowing Tristyn to twist away when they hit the ground. He ignored the pain in his side- had he broken a rib?- and breathed deeply, forcing air into his lungs as he staggered to his feet.

11, 12, and Rayne had disappeared, and 15 swore behind him but Tristyn had already taken off, following the direction he knew Rayne would take, up to higher ground, up the valley and to the road. 15 followed and Tristyn resisted the urge to turn around and stop him, to make him see that they were on the same side now, that he understood, but there wasn't time. Rayne was in danger, and every second he wasted was a second 12 could use to tear her apart.

But the decision was made for him- the was a whistling sound from behind and something snaked through the air and wrapped around him ankles, throwing him flat on his face in a spectacular fall that knocked the wind out of him once again. He tried to sit up, already scrabbling to untangle whatever 15 had thrown at him, but there was a sharp, precise blow to the back of his head and the stars exploded into blackness.