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."
The production will have scenic design by Steven Kemp, costume design by Jennifer Paar, lighting design by Josh Bradford and sound design and original music by Ryan Rumery.
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.