Complex sentence: When she tries to pursue the pair, Scully is surrounded by government agents and brought before Skinner and Leamus, who tell her that Mulder is infiltrating the New Spartans as an undercover agent.
Split into simpler sentences: When she tries to pursue the pair, Scully is surrounded by government agents and brought before Skinner and Leamus. They inform her that Mulder is infiltrating the New Spartans as an undercover agent.