In a rail car in Virginia, doctors working on Cassandra Spender are able to produce an incision that bleeds green blood before healing itself immediately. This is apparently the successful result of 25 years of experimentation, but the party is busted up by an alien rebel who sets everyone on fire...except Cassandra. Cancer Man pontificates about how the Syndicate's goal was to prepare a slave race of human-alien hybrids for alien colonists, and things were going just fine until the rebels showed up and his son (Spender) decided to betray him.
Cassandra is found alive at the train yard, and she wants to speak to Mulder. Spender is reluctant, but agrees to let them meet. A surviving doctor tells Cancer Man that Cassandra must be terminated, and a Syndicate elder is killed by a rebel. Scully thinks Cassandra's recollection might be able to expose the people who are doing the experiments. She and Mulder visit the now ambulatory Cassandra in the hospital. Cassandra spills the beans about how the aliens are taking over all life forms with the black oil, rebel aliens have mutilated their faces to prevent that from happening, and Spender's father is one of the people behind the colonization conspiracy.
The rebels are apparently causing the mayhem as a way of exposing the conspiracy, and the rebel has infiltrated the Syndicate disguised as the elder he killed; he suggests an alliance with the rebels. Mulder and Scully use Spender's computer to search for information on Cassandra's claim and find Cancer Man listed as C.G.B. Spender. Spender gets them in trouble for it, on the request of Cancer Man, but is starting to chafe under his orders. Scully has found that Cancer Man and Mulder's father were working together on a classified project with a doctor found at the train yard, and that Cassandra was first abducted on the same night as Samantha.
Cancer Man, having discovered the rebel spy, gives Spender a stiletto and orders him to kill the rebel. Spender botches the job, but Krycek finishes it; Spender is nevertheless freaking out to see the results and angered to learn that the group intends to sacrifice Cassandra for the greater good. Mulder and Scully let Skinner in on how the medical experiments have been ongoing, and Mulder thinks Cassandra is the first successful hybrid but also in danger of murder because the Syndicate doesn't want the project exposed. We see that Cancer Man, concerned over Spender's loyalty, has been talking to Fowley, and she agrees to help him. Cassandra flees the hospital and finds the agents, demanding that they shoot her "or it all starts." Mulder points his gun at her as someone bangs insistently on the door. To be continued...
Nick Tate, who plays Dr. Eugene Openshaw, played Alan Carter on the 1970s show Space: 1999.
Episode Body Count
Six doctors: torched by an alien rebel.
Dr. Eugene Openshaw: burned by an alien rebel, finished off when Cancer Man pulls the plug on his life support.
Second Elder: killed by an alien rebel.
Alien rebel: neck-stabbed by Krycek.
Krycek also mentions how a medical team in Arizona has been killed, but no numbers are given.
Cumulative Body Count (128/202 episodes, 1/2 movies)
Humans: 1,486Creatures: 100
Grand Total: 1,648
Updated to include an additional doctor after Fowley says the rebels have killed seven doctors in "One Son."