Ep 21. Meridian

After finding a planet that has an abundance of a rare mineral needed for their weapons, SG1 is ambushed by the Goa'uld and forced to dial the Stargate in order to escape. However, Daniel Jackson refuses to leave and stays on the planet to study an ancient device he believes holds great power.

As the rest of SG1 returns to Earth, they soon discover that Dr. Jackson's decision to stay behind was not without consequences. The ancient device he was studying causes a deadly radiation to start spreading throughout his body, leaving him with only a few days to live.

SG1 must quickly find a way to save their friend, but every attempt seems to be unsuccessful. As Dr. Jackson's condition worsens, he begins to shut himself off from those around him and starts to withdraw, causing tension and despair within the team.

In a final effort to save their friend, SG1 seeks guidance from an ascended being. The being offers a solution, but at a great cost, leaving the team to make a difficult decision.

As the episode comes to a close, SG1 is left to deal with the aftermath of their decision and come to terms with the loss of someone dear to them.