To save the world, Mars must invade Earth. The Earth is dying, overrun with pollution that the government refuses to stop. 16-year-old Tess is a proud Earther who wants to save the planet, but the government would rather ship everyone to Mars by force. And no one hears back from the Red Planet. When Tess's turn comes to board a one-way ship, she discovers a horrible truth: an alien race wants Earth for themselves. And Mars is a place where colonists struggle to survive. All Tess wants is to get back to Earth, but by running into Matthew, a fellow colonist with some secrets of his own, she gets wrapped up in a dangerous plan to do so: she must join an invasion of her former home. Tess has no choice but to face war. It's her duty. She's an Earther, after all. Or is she?