The growing tension between Oliver and Diggle puts both their lives at risk when they go after Damien Darhk and a H.I.V.E. deployed meta-human. Meanwhile, Laurel talks Thea into returning to Nanda Parbat to ask her father to put Sara into the Lazarus Pit. However, Laurel is surprised when Nyssa al Ghul (recurring guest star Katrina Law) refuses to do it.

In the season four finale, Oliver teams up with a surprising force in an attempt to stop Damien Darhk and his magic once and for all.

Clark learns that a Phantom Zone escapee has landed in Seattle and slaughtered the entire crew of a Taiwanese cargo ship. Upon further investigation, Clark comes face to face with the horrifying phantom, Aldar (professional wrestler BATISTA), who sucks the bones out of people. Meanwhile, a patient with the ability to travel between planes of existence escapes from LuthorCorp's secret experimental laboratory and seeks revenge on Lex.

Tragedy hits the set affecting the contestants and everyone behind the scenes.