The Fossil 2 (Secrets of Mars, #2)

For years, Filio Amorosa has had one goal, and only one goal: getting back to Mars. All that matters is finding out what happened on her mission there, and why she can’t remember any of it. But when she finally discovers the truth, it blows her whole world apart.

Meanwhile, on Earth, Agatha Devenworth and Pano Hofer have a new mission: travel from the Human Foundation’s secret underground base to New York to uncover what the enemy is plotting. Can they find a way forward for humanity in the midst of this clash of otherworldly forces?