Three years ago, in the quaint town of Truth or Consequences, a meteor crashed down on a New Mexico community, releasing an unknown parasite. A handful of operators from Tom Clancy's Rainbow Six Siege teamed up together and seemingly contained the mysterious parasite during the initial outbreak. Unexpectedly, the Chimera parasite has suddenly reappeared in multiple sites across the US, deadlier than ever and spreading rapidly. To monitor the parasite and prepare for any future threat, the Rainbow Exogenous Analysis & Containment Team (REACT), a highly specialized and outfitted organization led by Eliza "Ash" Cohen, Dr. Elena "Mira" Álvarez, and Jordan "Thermite" Trace, was created. Almost nothing is known about the evolving parasite, and REACT's hand-selected operators are the only ones suited to engage, push back, and learn about this deadly new threat. It is your mission to confront the mysterious creatures, known as the Archæns, who are now more lethal than ever before. Deploying into containment zones with the right combination of gadgets, gear, and teamwork will be integral to gathering the intel needed to stop them. With each incursion, you'll face the difficult choice of pushing deeper or extracting while hoping to save the operators in your squad from going MIA. Prepare to launch into thrilling, challenging, and often unpredictable missions as you and your squad risk everything together every time you step into the containment zone.