Since the early 1980s, hundreds of cryptic tiles have been found embedded in the asphalt of major intersections in Philadelphia, New York, Baltimore, Boston, Washington D.C., and as far south as Buenos Aires and Santiago.

They are roughly the size of an American licence plate, made from linoleum and pavement repair compound, and they all carry some variation of the same four-line message: TOYNBEE IDEA / IN KUBRICK'S 2001 / RESURRECT DEAD / ON PLANET JUPITER.

Nobody knew who was making them, how they were being installed undetected in major urban intersections, or what the message meant.

RESURRECT DEAD: THE MYSTERY OF THE TOYNBEE TILES (2011) follows Philadelphia artist and foot courier Justin Duerr, who first noticed the tiles in 1994 and spent the following decade trying to solve them.

Director Jon Foy, who dropped out of film school in Austin, sustained himself during the five-year production by cleaning houses and participating in medical research studies. He directed, filmed, edited, and scored the film himself. The score is one of the more unsettling things about it.

The investigation takes the team through a David Mamet play, a pirate radio operator, a Jupiter colonization organization, and the eccentric residents of South Philadelphia, before arriving at its strange, sad conclusion.

The film was selected for Sundance in 2011 and Foy won the Directing Award for Documentary. He has directed nothing since.

The tiles are still there. Philadelphia has preserved several of them.