“The Promise” is episode fifteen of season two of Arrow.
At the end of the previous episode, “Time of Death”, Oliver arrived home to discover that Slade Wilson was there with Moira. Oliver had previously given the impression that Slade was dead. This episode opens immediately after with Oliver asking Slade what he is doing there. It seems Slade has made a sizeable donation to Moira’s electoral campaign. Slade mentions the earthquake, saying to Moira that he knows how difficult it is to pick yourself up again after others have written you off. Slade also has a bottle of Australian rum, which appears to spark a memory with Oliver. Slade suggests drinking to friendship, and mentions the time Oliver spent on the island. It must have been hell for him.
On the island, Oliver is training and Slade congratulates him afterwards, Oliver says that trees don’t move, or shoot back, as Ivo’s men will. Slade suggests he shoot first. They needed a way onto the freighter and, from the downed plane in the previous episode – which was piloted by Sin’s father – they got a parachute.
After training, the attack on the freighter is discussed. Ivo’s men have GP25 grenade launchers, but no night vision, according to Sara. Sara is mixing up something that Oliver says smells awful. She tells him it tastes worse, but she knows Ivo, and it will work. Oliver wants to know what they should do with the Mirakuru. It may be a miracle drug, but people like Ivo should never get control of it. Slade, on hearing his name mentioned, agrees that the Mirakuru should be destroyed to keep it out of Ivo’s control. So, the box is burned.
Sara tells Oliver that Ivo devoted his life to finding the drug, and he wanted to save the world. She also tells Oliver he needs to kill Ivo as soon as he can. Otherwise, if Ivo gets the chance, he will make Slade think that Oliver was responsible for Shado’s death in “Three Ghosts”. The Mirakuru has made Slade unstable, and if he believes that Oliver is responsible for Shado’s death, he could completely lose it. Slade has a bottle of rum – the same type as he brought to the Queen mansion – to toast the mission with. 0liver wants Sara to tell his mother and sister, if he doesn’t make it, that he wasn’t the same person who got on the Queen’s Gambit. Sara, if she doesn’t make it, wants Oliver to tell her family she died on the Gambit. Oliver puts on Yao Fei’s hood and Slade takes out the black and white mask.
On the boat, Ivo is on the radio asking a doctor how a woman is. Apparently, her condition is progressing quicker than expected. This may be Ivo’s real reason for looking for the Mirakuru. Knyazev is brought in and strapped to a chair. He offers Ivo millions, but Ivo doesn’t need money. He does need one of Knyazev’s eyes though.
Oliver has lit a fire arrow and shoots at a bonfire on the beach. He misses with the first shot, which brings a comment from Slade, but hits with the second. Ivo notices the fire and sends arm men to bring Oliver and the others back – alive. Oliver, when the men approach, runs away, then trips and falls. He is taken to Ivo, who injects him with sodium pentothal – often, somewhat erroneously, referred to as truth serum. So Oliver will tell the truth.
Back in the mansion, Oliver is trying to get rid of Slade, who wants to see the rest of the house. He even tries stabbing Slade, when Moira leaves the room, but the Mirakuru has made Slade far stronger. Then Thea arrives. Slade wants to see all of Oliver’s family.
Far more time is spent on the island than is typical, with the raid on the freighter. Given all the attention spent planning, Oliver being so easily caught seems a little off, so perhaps it is part of the plan. Slade and Sara are still out there. Back in the present, Oliver and Slade are saying many things to each other, and many of them have double meanings, referring to events from their joined past. Given that the raid on the freighter is going ahead, it seems highly likely that this is when Slade finds out about what happened when Shado was killed, and therefore what turned him from Oliver’s friend to his enemy. Oliver does manage to get word out to the others – including Roy, who Oliver revealed his true identity to in “Tremors” – and Sara, of course, recognises Slade’s voice. Even if it’s that of a man she thought was dead.