Los Angeles' power grid is taken hostage in a ransomware attack resulting in a citywide blackout.
Oliver is ready to get back to work with the SCPD and to focus on his marriage with Felicity. However, when Dinah tasks Oliver with tracking the new Green Arrow (new series regular SEA SHIMOOKA) things take a surprising turn. Meanwhile, Diggle and Lyla must answer to ARGUS about Diaz (recurring guest star KIRK ACEVEDO).
After months of covertly pursuing Dante, Diggle and Lyla finally have a solid lead on the elusive terrorist, so they deploy the ARGUS Ghost Initiative to apprehend him. Meanwhile, Oliver tries to bond with Emiko.