A walk-in agent is an individual who voluntarily offers to conduct espionage. Specifically, a "walk-in" is an agent or a mole of a government who literally walks into an embassy or intelligence agency without prior contact or recruitment.
Famous quotes containing the words walk-in and/or agent:
“With four walk-in closets to walk in,
Three bushes, two shrubs, and one tree,
The suburbs are good for the children,
But no place for grown-ups to be.”
—Judith Viorst (b. 1935)
“The average American is a good sport, plays by the rules. But this war is no game. And no secret agent is a hero or a good sport—that is, no living agent.”
—John Monks, Jr., U.S. screenwriter, Sy Bartlett, and Henry Hathaway. Robert Sharkey (James Cagney)