"Piper Maru," the 15th episode of The X-Files' third season, introduces the "Black Oil," a sentient, radioactive alien substance that infects a salvage crew in the Pacific. This pivotal episode follows Fox Mulder's investigation to Hong Kong and links a 1945 submarine incident to a modern conspiracy, while Dana Scully faces internal Bureau corruption. For comprehensive details, visit Piper Maru | X-Files Wiki - Fandom . Season 3 - Piper Maru (1) (1996) - (S3E15) - Cast & Crew