CIA analyst assigned by President Henry Hayes, through General George Hammond, to serve as personal assistant to the recently promoted Brigadier General Jack O'Neill -- while in fact he was to secretly "audit" the General's performance as leader of Stargate Command. Previously responsible for background checks, Gilmour's high security clearance allowed him to arrive undercover as O'Neill's new administrative aid.
Mr. Gilmour's post at the S.G.C. lasted only five days. While there he witnessed General O'Neill deal with delegates from planet Amra; a fast-growing plant SG-8 brought back from P6J-908; an apparent kidnapping of SG-1 by the System Lord Baal; and feeble pleas for additional freedoms by the Goa'uld Camulus -- not to mention avert the destruction of Earth's solar system by a Zero Point Module that Camulus had rigged to explode upon use.
Eventually successful at dealing all the cards in the deck, it was clear to Gilmour that O'Neill was the right man for the job. As the President's motorcade reached Cheyenne Mountain for an official visit Gilmour revealed his true purpose -- but he was surprised to learn that General Hammond had let Jack in on the plan from the beginning.
Zero Hour - Mark Gilmour is assigned as an undercover spy to determine whether or not Jack O'Neill is suited for command of the S.G.C.