Mark Gibbon

An edgy janitor takes Clark's high-school class hostage at LuthorCorp, claiming his jitters were caused by a mysterious contaminant.

Clark is unsettled when a class project has Chloe delving into his past, and Lex has problems of his own when a man he thought long dead turns up seeking vengeance.

Ryan (from "Stray") returns and Clark has to save him from Dr. Garner of the Summerholt Research Facility. Meanwhile, Aunt Nell leaves Smallville, and Lex wants to expand the plant but runs afoul of the mayor.

Former DA Raymond Sacks threatens Lois after he is released from prison; Chloe discovers Zod's secret.

Mary Margaret pays a visit to a comatose John Doe in the hospital, and Prince Charming unexpectedly meets Snow White for the first time back in the fairytale world.