Ep 15. Chain Reaction

General Hammond finds himself in a difficult situation when a former NID Agent contacts him and informs him about a rogue NID operation that could potentially harm Earth's security. As a result, Hammond has to make some tough choices about whom to trust and what actions to take to prevent any damage to his home planet.

The episode starts with General Hammond at a briefing discussing the NID (National Intelligence Division), America's covert intelligence agency, that has long been suspected of conducting unethical and illegal operations. As they are discussing this, a former NID Agent, Malcolm Barrett, walks in and demands to speak with Hammond. Barrett tells Hammond that he has information about a rogue NID operation that's about to take place. Barrett warns that the NID’s plan could have grave repercussions on Earth’s national security. Barrett’s information is classified, and he's hesitant to share everything with Hammond, stating that he is afraid of being killed.

Hammond is astonished and surprised to hear from Barrett. He's well aware that Barrett was sacked from the agency for being an extremist and deemed a liability. Having no idea how to proceed, General Hammond decides to contact SG1 and request their assistance. SG1 agrees to help Hammond, despite being unsure about trusting Barrett’s claims. General Hammond informs SG1 that he has limited time and they need to act fast.

Meanwhile, Barrett has been followed, and a NID hit team plans to eliminate him and SG1. A fire-fight ensues, and Barrett is killed while SG1 is trying to counter-attack. The team does, however, manage to retrieve a “cubit” – the device that Malcolm had acquired and which he claimed played a crucial role in the NID's operation.

The cubit has a peculiar, luminescent glow when activated, and SG1 concludes that it might be a device that can generate immense energy. Initially, SG1 decides to keep the cubit secure and safe on a remote base. However, problems start to arise when Earth's energy infrastructure starts malfunctioning. The cubit manages to interfere with Earth’s power grid, causing the energy system to overheat, putting millions of lives at risk.

Hammond frantically contacts SG1 to investigate the situation and find out what is causing the malfunction. SG1 is initially baffled, but they soon discover that the cubit is the primary cause of the problem. They quickly decide to destroy the device by dispersing it across the universe through the Stargate. SG1 dials up a Gate address and throws the cubit into the wormhole. The cubit is destroyed in the process.

Hammond is relieved and grateful to SG1 for managing to avert a major catastrophe. The episode concludes with General Hammond reflecting on the incident and the unending battle for Earth's security. He acknowledges that SG1, despite their limitations, will always be Earth’s first line of defence against extraterrestrial threats.

“Chain Reaction” is an intense and fast-paced episode with multiple action sequences that are sure to leave viewers on edge. The episode continues the series' strong focus on the complicated politics and conspiracies that exist both within the Earth’s and other planetary political landscape in the Stargate SG1 universe. It touches upon the theme of trust and loyalty while also highlighting the importance of making difficult decisions for the greater good.