"Arrow" alum Colton Haynes will guest star in the upcoming second season of the Fox horror-comedy "Scream Queens."

The setting of the Ryan Murphy series will shift from fictional Wallace University to a hospital owned by Jamie Lee Curtis' Cathy Munsch and the Chanels (once again played by Emma Roberts, Billie Lourd and Abigail Breslin). John Stamos and Taylor Lautner will play doctors.

Entertainment Weekly reports that Haynes has been cast in a mystery role, presumably that of a patient.

A veteran of MTV's "Teen Wolf," Haynes debuted during "Arrow's" first season as Roy Harper, a street thug who went on to become Arsenal. The actor was a series regular throughout seasons 2 and 3, until his departure in 2015. He returned as a guest star in Season 4.

"Scream Queens" returns Tuesday, Sept. 20, on Fox.