Presented mostly in extended flashbacks to the island, and back in the present with Oliver (Stephen Amell) being forced to humor the devil in their midst when Moira (Susanna Thompson) and Thea (Willa Holland) show Slade Wilson (Manu Bennett) around the Queen home, “The Promise” deals with the relationship between the two men and the series of events which turned friend into enemy. The well-coordinated attack on Ivo’s tanker succeeds as Oliver, Sara (Caity Lotz), and Slade take the ship but when Ivo tells Slade the circumstances under which Shado (Celina Jade) died everything goes straight to hell.
Thanks to the open line of Ollie’s cellphone, Sara realizes the situation his family is facing should the long-simmering grief-stricken killer choose to exact his revenge and takes both Diggle (David Ramsey) and Roy Harper (Colton Haynes) into a battle that Slade sidesteps rather easily, keeping his cover as a generous polictical support of Moira’s mayoral campaign and allow Ollie to further stew knowing Deathstroke’s plan is just beginning.
“The Promise” offers more sequences on the island in a single episode since early in Arrow‘s First Season. It also marks a turning point in Oliver’s stay in the island, now on the barge under Deathstroke’s control, which should further illuminate more of the future vigilante’s time away from Starling City. Next week’s episode offers the return of several characters including Deadshot (Michael Rowe) and Bronze Tiger (Michael Jai White) as Lyla (Audrey Marie Anderson) asks for Diggle to join the Suicide Squad.