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; Lex has problems of his own, when a man he thought long dead turns up seeking vengeance.
Clark tests the limits of his powers in order to save his young telepathic friend Ryan from an evil doctor who wants to control the boy's abilities; Aunt Nell leaves Smallville; Lex has a run-in with the mayor.
Emma talks Mary Margaret into reading to an unidentified coma patient in the hospital; Prince Charming and Snow White meet for the first time.
Former DA Raymond Sacks threatens Lois after he is released from prison; Chloe discovers Zod's secret.