It's 1916, and Warwick Easton's traveling show has landed him in California. Out of money and about to return to England, Easton gets lucky when silent movie star and "King of Comedy" Mack Sennett offers him a job performing slapstick comedy stunts as a Keystone Cop.

At Keystone Film Studios, he runs into silent-era comedy legends, including Mabel Normand and Roscoe "Fatty" Arbuckle, but the laughs turn sour as things quickly start to go awry. Known in his new role only as "Keystone," Easton finds the line between cop and comedian starts to blur, especially when a series of tragedies strikes the studio. The gory death of a stunt actor on a roller coaster seems like an accident, but then a bludgeoned body is discovered in a bungalow and Amber Honeybee, the beautiful but troubled actress Easton has befriended, vanishes. Easton has no choice but to step into the role of a real detective. Does he have what it takes to unravel the mystery in time and save the girl?