Farrell replaces the previously announced Hal Robinson, who withdrew for "personal reasons."
Directed by Jonathan Silverstein, the production will officially open March 5 at 7 PM. Performances continue through March 24.
The Old Boy, according to press notes, is "the story of a successful politician who returns to his elite prep school to dedicate a building to his best friend, only to discover he may have been responsible for his death."
Show times will be Tuesday at 7 PM, Wednesday-Friday at 8 PM, Saturday at 2 PM and 8 PM and Sunday at 3 PM.
Performances will be at The Clurman Theatre at Theatre Row (410 West 42nd Street, between 9th and 10th Avenues). Tickets, priced $62.50, may be purchased online at Telecharge.com or by phone at (212) 239-6200 or in person at the Theatre Row Box Office.
For more information visit www.keencompany.org.