A routine rendezvous becomes a desperate fight for survival when the USS Horizon answers a distress call from a crippled Federation Starship. With lives handing in the balance Captain Tahlari Vahl and her crew launch a massive rescue operation, only to discover that the attackers have not finished what they’d started. As casualties mount, systems fail and a relentless enemy returns to claim its target, the Horizon must stand as the only barrier between catastrophe and those depending on its protection. In the face of impossible choices, the crew will discover how much can be demanded of those who hold the line.