Can Robin and Guy rescue Archer?

In York, Robin and Guy's half brother, Archer, is imprisoned in the castle dungeon for failing to deliver a consignment of arms from the East. But he's been conducting an affair with the Sheriff's wife, Gweneth, who tells her husband that Archer has the alchemist's knowledge to turn iron into gold.

He's brought before them to illustrate his talents and, using gunpowder to create a distracting explosion, replaces an iron nail with a gold nugget, claiming a miraculous transformation. But the Sheriff soon discovers Archer and Gweneth in a compromising situation and sentences him to be boiled in oil and beheaded.

Robin and Guy reach York and struggle to find a way into the dungeons, but it's not long before Guy is arrested after a tavern brawl and thrown into Archer's cell. Robin steals a rich merchant's clothes, bargains with the Sheriff for Guy's release and, once in the dungeons, frees Guy and his brother. But, as they struggle to find a way out, they are surrounded by the Sheriff's guards and Isabella's captain, who offers a reward for them.

The Sheriff, however, wants them hanged and they are taken to the square to be executed. But Robin's men are in the crowd and Gweneth, too, plans to help. One of her servants places Archer's black powder in a brazier causing a huge explosion and, in the confusion, the three prisoners escape.

Safe at last, Guy and Robin ask Archer for his help in their fight against Isabella and Prince John. But Archer has his own plans, stealing Guy's horse and riding for Nottingham... and Isabella!