Felicity learns something new about Oliver that shocks her. Meanwhile, Diggle asks Curtis to go undercover for ARGUS. Dinah works with an unlikely ally.

Rene fights to help the new Green Arrow's mission, and Oliver, now working with the SCPD, finds an unexpected link to the mysterious vigilante.

After the Ninth Circle delivers a major setback for Team Arrow, Diggle reluctantly reaches out to a Four-Star General of the Defense Intelligence Agency for help, despite unresolved tension from their past. Meanwhile, Oliver discovers a piece of information that he believes will turn Emiko against the Ninth Circle. Alena returns with an interesting proposal for Felicity.

Upon learning the key to oppose The Monitor, Oliver and team return to Russia on a mission to gather the necessary materials. Connor reunites with a figure from his past.