Chloe was a normal girl who was about to have her life turned upside down. The Doctor runs into Chloe's life after a failed alien attack and totally changes her life. Now Chloe has to deal with the new memories of her past and everything that is going wrong in the present.

Stranded on a parallel Earth, the Tenth Doctor finds himself mentoring a traumatized child soldier enlisted in a hopeless war to save humanity. With an endless number of mysteries in sight -- from the enigmatic alien invaders they call Angels, to the strange machines known as Evangelions used in the planet's defense, to the shadowy maneuvers of those in power -- the Doctor is drawn deeper and deeper into a web of mistakes and sins that threaten to consume all humankind. In time, he'll face the darkest question of them all: what if there are some worlds -- and some children -- even the Doctor can't save?

Quotes from Doctor Who (in case the title was unclear). All rights to the BBC.