Eight months have passed since the incident aboard Pluto Station Six. The survivors from the Berlin mission, as well as most of the Space Corps, have been searching for the Thlelolelan asteroid ship which is still at large somewhere in the solar system. Captain Joseph Sims and Captain Sarah Brillow each have a command of their own and are desperately hoping that their extended hunt will soon end. The public remains optimistic that the alien ship will eventually be discovered and its unknown intentions exposed. But when news of an attack on a Lunar Sovereignty colony on Mars' moon Phobos starts to spread, Director Burnham recalls most of the crew from the Berlin mission, as well as some new faces, to investigate this incident. It seems the Thlelolelans are interested in continuing their mission and their first task is demonstrating their supreme power to the people of Earth. They hope to frighten humanity into submission so they can 'dig their tunnels' without interference. With time running out, the Space Corps officers must scramble to find a way to stop the approaching asteroid ship before they can unleash their might on our home planet...