Media report, KXLH.com, 22 September 1999:
"The FBI and the Wheatland County Sheriff's Department are still mystified by the disappearance of a team of U-Penn archeologists from the Big Porcupine Creek area. While the FBI are tight-lipped, sources within the investigation have confirmed that the disappearance has been linked to that of University of Montana-Helena grad student Franklin Opetz, and that Dr Thomas Thorley is a prime suspect in the investigation. Dr Thorley has not been since since escaping from the custody of the Wheatland County Sheriff's Department a week ago, having been arrested after reportedly threatening the U-Penn team with a shotgun. U-Penn archeologists Dr Emmett Wilson, Larry Kazal, Denise Oester, and Gareth Wylin disappeared sometime on September 8 from the Harlowtown, MT Motel 6 where they had been staying..."

NSA Call Transcript, 09-08-1999 15:35Q (19:35Z) OR [REDACTED] RP [REDACTED]
Wylin, Gareth, working through Charlie for the group. 
Ah, Jesus. Everyone is gone. 
Wilson was the first to go, and he just, like, went... away. But now, and I mean its just been minutes. 
Gone. All gone.
Everyone here, at the dig. We're digging at Big Porcupine Creek, near Harlowtown. Harlowtown, Montana. [static] 
[B]ut I couldn't do it. Its something about the antenna we dug up. Something... 
[prolonged static] 
Hair's standing on end... something— [MESSAGE ENDS]

DELTA GREEN is an illegal conspiracy within the US government. Its purpose is to protect the United States from preternatural threats. When they detect one, they have three tasks: find it. Kill it. And cover it up.

This scenario is from DELTA GREEN: EYES ONLY, but will be run under the Cthulhu Dark system.