The Saddest Lines by Amanda Rex G. Mulder's thoughts during "Arcadia" after Scully kicked him out of the bedroom. [Note: This is an external link]

Salvation by Humbuggie MT. UST. MSR. When a desperate mother contacts Mulder to find her daughter who ran away to join a cult, Mulder gets an unforeseen chance to deal with his past. But when he infiltrates the cult, Scully must do everything in her power to save her partner from his 'salvation'.

Sand Castles by mercury MSR. NC-17. Set post-"Arcadia", Mulder and Scully have some fun when they go undercover as a married couple.

Secret World by Bonetree S, A, X-File. Rated R. Novel. Scully goes deep undercover to find the secret behind a mysterious death. But with what she learns, will she ever be able to come in from the cold? [Note: this is an external link.]

Shadows in Silence by Hiding in the Light XRHA. Mulder and Scully go undercover as bird-lovers toinvestigate a case located in one of the government's most beautiful national parks. What begins as routine almost instantly turns into a race against man playing God, the darkness of the past hidden in the Virginia mountains determined to break through the silence.

Shakespirited by mimic117 X, MSR. PG-13. When the members of a small Shakespearean company start dying, Mulder and Scully go undercover to investigate. But will they discover what is killing people, or will they be next? (This story was written for Virtual Season 9.) [Note: This is an external link]

Shimmy by Skylarking Humor, MSR. NC-17. Skinner sends Mulder undercover, though, not much of it...

The Shipp Clinic by Kel PG. MSR. H. Mulder & Scully are sent to a relationship Clinic to find the device that supposedly forced someone in the Executive Branch to behave amorously.

Sleepless Nights by Spookette MSR. Mulder goes undercover, and Scully is worried-- but will a chance meeting put her in danger?

Snapshots by Dawson Rambo PG. MSR. A. A series of vignettes that culminates in an undercover assignment with benefits.

Sore Luck at the Luxor by Anubis Mulder and Scully go undercover in Las Vegas, as high rollers at the Luxor Hotel.

Soft by banlu PG. MSR. An undercover assignment to catch a stalker at a wedding leaves Scully a little tipsy and vulnerable.

Something Wicked by Donnilee & FatCat NC-17. MSR. Mulder and Scully are assigned to expose a serial killer after several drug land-style executions. But, are things really as they seem?

Speedo Optional by Thalia D'Muse R. H. X. MSR. A string of bizarre murders send Mulder and Scully to a secluded resort in Florida.

Stain of Purity by Nicknoc NC-17. MSR. Casefile. Mulder and Scully investigate a series of abductions.

Subterfuge by Xanthe NC-17. BDSM. Slash. A ritualistic serial killer is on the loose and, in order to trap him, Mulder and Skinner must go undercover in the gay BDSM underworld with Mulder playing errant submissive to Skinner's stern top. [Note: This is an external link]

Surfaces and Depths by Branwell S, A, MSR. Mulder, Scully and Skinner work undercover to trap a bomber. They have secrets and suspicions among themselves.

Tantric by TBishop MSR, X-File. NC-17. Mulder and Scully go undercover to the Church of Seven Chakras... and their relationship is changed forever.

Thank You, Drive Around by nevdull PG. Undercover assignments come in all shapes and sizes. Scully's not sure she appreciates this one.

Thank You For Shopping At K-Mart by Brandon D. Ray PG. UST. Mulder and Scully go shopping in Arcadia and unexpectedly run into someone they know.

This House is Burning series by Tesla. Casefile, MSR. Mulder and Scully go undercover at a ski resort with two other agents. Mulder's profiling, Scully's the decoy and she's having trouble sleeping. [Note: this is an external link]

To Die For by Myriss PG-13. You never know who you might pick up at a bar.

Tranquility Lost by Debra Longley. Angst, UST/MSR, X-File. R. Posing as a bickering married couple, the agents investigate Tranquility, a spa where all-body treatments and stress reduction activities go hand in hand with mind enrichment. Is Mulder taking his role way too seriously or is something more sinister involved? (This story was written for Virtual Season 9.)

Truckin' by Donnilee & FatCat NC-17. Mulder and Scully go undercover as an over the road, married driving team to break up a hijacking ring.

Trust by Donna G. Important men are being murdered. Scully goes undercover as a high-priced escort to find out.

Undercover by Lee Burwasser G. Just how literally "undercover" can you get?

Undercover by croyant PG-13. UST. Scully goes on an undercover assignment without Mulder. But does she know what she's getting into?

Undercover 1 & 2 by Danielle Culverson R. X. Mulder and Scully go undercover to Nebraska to investigate some murders, and discover that working so closely has both advantages and disadvantages.

Undercover by Nichole UST, MSR, Angst. Scully is assigned to an undercover investigation. Mulder is deeply troubled and needs to get something off his chest before she goes.

Undercover by Raven D/s. Slash. An undercover operation reveals the possibility of romance and love between Mulder and the AD. [Note: This is an external link]

Undercover Horror by Denise Schoppe G. MSR. H. Scully goes undercover. . . as a third grade teacher.

Undercover Lovers by Angela W. R. M/S married. Mulder, Scully and their daughter go undercover to help Skinner catch a cop killer.

Undercover Operation by Angela W. NC-17. MSR. DRR. Four FBI agents go undercover. Four very lonely women come to visit them.

Undercover Work by Donna UST/MSR, R. When an undercover investigation hits Scully too close to home, can Mulder help?

University by Jess M X-file, UST. PG-13. Mulder and Scully go undercover at a University and come in contact with a whole lot of subliminal messages.

Viva Las Vegas and All That by Macspooky Humor; "an unromantic romance". NC-17. Skinner sends Mulder and Scully undercover to an Elvis Wedding Chapel in Vegas.

Walking in Sunlight by Summer M. MSR. Mulder and Scully go undercover as newlyweds, and new facts are brought to light.

Walking With Wolves by Xandra MSR. X. A. Scully is at the mercy of a band of escape con's of which Mulder is a part.

The Wall by Xanthe M/Sk. Slash. Skinner goes undercover in a drug gang to find out what's happened to an old friend from his days in Vietnam. Mulder, of course, can't let him do it alone. [Note: This is an external link]

We're in Love by Jammer PG-13. MSR. Mulder and Scully go undercover as a married couple. During a snowball fight they realize something.

The Winklers by Michelle Ferguson. MSR. Mulder and Scully are forced to masquerade as newlyweds at a marital retreat.

Yee-Haw by Satina MSR, UST, MulderTorture. NC-17. Mulder and Scully go undercover at a dude ranch to investigate some suspected cult involvement. Mulder sustains some injuries that only Scully can adequately treat.