Ep 21. Zero Sum

In The X-Files season 4 episode 21, titled "Zero Sum," Agents Mulder and Scully investigate a series of bizarre and seemingly unrelated murders in Washington, D.C. The case becomes even more complicated when they discover that all of the victims had been injected with an unknown substance that causes their brains to malfunction and become uncontrollably violent.

As the agents delve deeper into the case, they uncover a tangled web of deception and corruption that leads them to a powerful pharmaceutical company called Roush Technologies. Mulder becomes convinced that the company is involved in a sinister conspiracy to control people's minds and exploit their fears.

Meanwhile, Scully finds herself struggling with her own ethical dilemmas as she is pressured by her superiors to help cover up the company's involvement in the murders. She must decide whether to risk her career and her life to do the right thing, or to play it safe and turn a blind eye to the truth.

As the episode unfolds, tensions rise and the stakes get higher as Mulder and Scully race against time to uncover the truth behind the mysterious substance and bring the perpetrators to justice. With its thrilling plot twists and gripping suspense, "Zero Sum" is an unforgettable episode of The X-Files that will keep audiences on the edge of their seats from start to finish.