Mark endures a reintegration-induced seizure, intertwining his past with Gemma and Lumon's dark experiments. Revealed alive, Gemma faces continuous testing in Lumon's facility. The episode delves into their relationship, fertility struggles, and Gemma's current torment, highlighting themes of death and rebirth. Devon seeks unconventional help for Mark, while the mysterious "Cold Harbor" project subjects Gemma to emotional tests.