Reunited with his sister, Oliver and Thea find themselves searching through a familiar maze of catacombs. Meanwhile, John and Lyla partner on a special ops mission.

Oliver, John, Laurel, and Tatsu seek out an important person within the Monitor’s plan. Connor has a heart to heart with his brother.

Oliver returns to Starling City on Earth-2, where he encounters familiar faces while trying to decipher the Monitor’s mission. Meanwhile, Mia and William’s team clash with a new foe.

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…

The Intelligence Unit works to find the bombers. Even with government agencies in the mix, Voight and his team work the case from their own angles and connections. Lindsay and…

Halstead’s badge is revoked when Lonnie Rodiger is found dead; Severide and Clarke find Dr. Elliot’s torso; Sumner tries to prove herself; Lindsay shares a moment with Severide.