Gisborne has taken the boys back to Locksley Manor where the Sheriff orders that they be hanged. Luckily, Robin and his gang arrive in the nick of time. What's more, Robin cleverly steals the impressive black diamond, used to create the Damascus steel. But disaster strikes and Daniel is captured during the scramble.
The Sheriff immediately demands an exchange – Robin can have Daniel back if he hands over the black diamond. Robin's priority is rescuing Daniel and he and the gang decide that they will agree to the exchange and, once made, they will then set light to the diamond's box and melt the black diamond once and for all.
Marian learns of Daniel's capture and puts a plan into action. Feigning interest in seeing Gisborne, she requests a night pass from the Sheriff. She doctors the document so that the signature can be mistaken as a release for Daniel. Marian runs her plan past Robin as she needs one of the outlaws to pose as a guard and take Daniel. To everyone's surprise, Allan volunteers, but he only sees it as a brilliant opportunity to leak Robin's plan to Gisborne.
Once Gisborne is forewarned of Robin's plan, he arms himself to the hilt, donning his indestructible suit of armour. Now a rescue attempt is virtually impossible and Robin must think fast if he's to save a boy's life and stop a vital part of the Sheriff's war machine.
Robin and the Sheriff meet, ready for the exchange. The Sheriff demands that Robin takes part, otherwise, the archers will shoot on Robin. Robin agrees. Marian takes the boy, scared for his safety. Robin hands over the box, lined with pitch inside; they plan to shoot a flaming arrow, the pitch lights, the rocks explode. However, the Sheriff knows about this plan because of what Allan told Gisbourne, and takes the rocks out of this box. He walks away happy and tells Gisbourne (in hiding) that Robin is all his. Gisbourne is revealed in his indestructible armour. As he goes to attack Robin, it seems all hope is lost. Robin can only dodge away; his attacks make no difference to the armour. But good always triumphs over evil, as he finds a bucket of pitch. He throws it over Gisbourne, who cannot understand why this is such an attack. Robin lights an arrow from a nearby fire, causing The Sheriff to say: "Oh, no." To which, of course, Robin replies: "Oh, yes." He shoots the arrow, setting Gisbourne's armour alight.
Gisbourne climbs into a water container to extinguish the flames, and Robin follows him. He takes off the helmet and breastplate, holding Gisbourne at swordpoint. He then calls to the Sheriff for another deal: He will let Gisbourne live if the Sheriff surrenders the rocks to him. He asks how long Gisbourne can hold his breath before pushing him under the water. The Sheriff downplays Gisbourne's importance to him, with Gisbourne calling to him every time Robin lets him up. Marian sees that the Sheriff will let Gisbourne die, and threatens the blacksmith. (He is the only man who can make the steel). The blacksmith is scared for his life, and tells the Sheriff that he will get more rocks. The Sheriff eventually throws the rocks to Robin, who lifts Gisbourne out of the water.
Gisbourne is seen taking off the armour, and sees Marian. He tells her that he has been assuming she has had nothing to do with Robin Hood since he became an outlaw. She agrees that this is true. He warns her that it had better be true, because otherwise, the punishment is death. She asks him if he would rather that she let him die, and he does not reply. The Sheriff appears, chasing after the blacksmith, who claims he is going to France because he cannot work under these conditions.
After the blacksmith disappears, the Sheriff takes his anger out on Marian. She tells him that she only did what she did because Guy is his loyal servant, and she could not let him die. Guy is in the background and looks skeptical as Marian acts as though she may still have feelings for him. He knows that Marian does not have feelings for him, but he says nothing. Marian tells the sheriff she was stopping him from making a mistake. He tells her it is not her place to do that, and she will be punished. Marian tells him mockingly that she is ready for his punishment. The Sheriff asks if her father is. Marian is stricken with worry for her father.
The episode ends with Robin Hood giving the four boys the wooden tags that signify that they are part of Robin Hood's gang. They all call: We Are Robin Hood.