The mystery of Scully's pregnancy is revealed and the thread of an alien invasion becomes a reality on 'The X-Files' this May on FOX.

David Duchovny Appears In All Four Episodes; Annabeth Gish Guest Stars In Two-Part Season Finale

Agents Mulder and Doggett investigate mysterious deaths aboard an oil rig in the Gulf of Mexico, Doggett becomes the hunted target of a deadly creature and the mystery of Scully's pregnancy is revealed on THE X-FILES Sundays, April 29, May 6, 13 and 20 (9:00-10:00 PM ET/PT) on FOX.

In "Vienen" April 29, Agents Mulder (David Duchovny) and Doggett (Robert Patrick) are begrudgingly thrown together to investigate several mysterious deaths aboard an oil rig in the Gulf of Mexico. Mulder believes the deaths on board to be part of the alien conspiracy and races to convince the skeptical Doggett that the ship may not be pumping traditional oil.

With Scully (Gillian Anderson) on leave due to her impending delivery and Mulder barred from his official investigative duties, Doggett, with the aid of a new and very green FBI agent (guest star Jolie Jenkins), finds himself hot on the trail of a deadly creature in "Alone" May 6. But when the situation reverses and Doggett becomes the hunted, Mulder and Scully must race to rescue him before the creature makes him its prey. This episode was written and directed by executive producer Frank Spotnitz.

In the two-part season finale "Essence" May 13 and "Existence" May 20, long-simmering plot twists converge and details about Scully's pregnancy are revealed as Mulder, Doggett and Skinner (Mitch Pileggi) must work together to protect her unborn child. The agents, with the help of agent Monica Reyes (guest star Annabeth Gish), must put aside their differences and band together, as shadowy forces endanger Scully and her child, and questions regarding a possible link to an alien invasion surface. The two-part season finale was written by creator and executive producer Chris Carter and directed by Kim Manners.

Chris Carter is the creator and executive producer of THE X-FILES, which is produced by Ten Thirteen Productions in association with 20th Century Fox Television. Frank Spotnitz and Vince Gilligan also serve as executive producers. Michelle MacLaren, John Shiban and Kim Manners are co-executive producers; Paul Rabwin, Harry V. Bring and David Amann are producers.