Urban Decay (2007)

Cab driver Stan slams into a homeless man who gets up and walks away, leaving behind a scarf covered with writhing maggots. Obsessed with the mystery, Stan hunts the figure through the city, discovering a trail of mangled, half-eaten victims, and an urban legend: Puss Head was a sewer worker who came back from an uncharted tunnel changed into something both living and dead. Parents warn their children that the shuffling zombie will get them if they stay out on the streets too late. But as the body count rises, Stan finds that the legend is alive and hungry.