United Planet Earth's best exploration spaceship, Ticonderoga, is in trouble, and her retired captain, Allison Mackenzie, is the best person to attempt the rescue. In orbit of Mars, Ticonderoga is losing its power and life support. Allison teams up with a skeleton crew of fresh faces and sets out aboard the hastily prepared rescue ship, Lexington. On the way, a poorly understood spatial phenomenon endangers Lexington and makes Mackenzie doubt her ability to see the mission through. Can Allison bring home both crews and ships and help Earth understand the phenomenon that is wreaking havoc across the solar system?