First aired on January 6, 2004 , " Grace " is often cited by fans as one of the most unique and character-driven episodes of the series. Shifting away from the usual ensemble action, it provides a deep dive into the psyche of Major Samantha Carter as she faces an isolated crisis in deep space. The Plot: Stranded in the Nebula

While the Prometheus is en route to Earth, it is intercepted by a massive, unidentified alien spacecraft. Outgunned and under fire, Carter orders the ship into a nearby nebula-like anomaly to escape. The maneuver succeeds but leaves Carter unconscious. When she awakens, the entire crew is missing, the ship is dead in the water, and she is suffering from a serious concussion. What is the unknown ship in Stargate season 7 episode 13?