After 2 years in space, a satellite is returned to earth and is found to have a mysterious substance on its outside surface. Tamara is called in to help in the investigation until Keith Mason and his team from Ames Research push her aside and exclude her from valuable information. Tamara has, however, reserved a sample and does her own research, enlisting D.B.'s help, and discovers that amazingly enough, the substance contains living cells. Mason finds out what she has done and takes steps to bar her completely from further involvement. For the first time Tamara begins to realize that there is more going on than she ever suspected and realizes that she will likely never find out the truth behind what she has found. Meanwhile, while preparing for his first Shuttle mission, Reggie makes the (well-intentioned) mistake of allowing a friend to sleep at his place for a few days. The distraction of a loud houseguest and the stress caused by lack of sleep have him making careless mistak

An elated Reggie Warren has finally realized his dream and has made it into space on a routine mission of a construction EVA and scientific reasearch. All does not go well for long, however, turning his dream into a nightmare. While Reggie and Japanese astronaut Hiro Furukawa are outside the orbiter on an extended EVA there is an accidental release of mercury sulphur gas during one of the experiments inside of the shuttle. On their return inside they find the 2 scientists disoriented, sweating and confused as to what has happened. Reggie must muster all of his faculties to return the Shuttle back to earth and save himself and his crew as he realizes that he too has been exposed to the toxic gas.