Unchained

"Unchained" is the upcoming twelfth episode of the fourth season of Arrow and the eighty-one episode overall.

Synopsis
The team faces off against a formidable villain nicknamed The Calculator. Meanwhile, Nyssa makes her move and Roy Harper returns to Star City.

Production
Preparation ran from November 10 until November 19, 2015. Shooting ran from November 20 until December 3, 2015.