The Sheriff unleashes his weapon of mass destruction

Robin and his men are trapped inside Nottingham's city walls, surrounded by Vasey's army. In a show of power, the back-from-the-dead Sheriff unleashes his trebuchets - mighty catapults that hurl missiles of deadly Byzantine fire into the city.

Robin has to stop them and leads a small party of men out to sabotage the machines. When the soldiers fire them, the missiles fall back onto the trebuchets, engulfing them in flames. In retaliation, Vasey's soldiers smash through the city gates but are stopped at the castle itself. Frustrated, the old sheriff orders some of his men into the secret tunnel that leads to the castle.

Meanwhile, Isabella escapes from her cell and heads into the tunnel. Guy follows her but is suddenly faced with Vasey and his men – Isabella was part of the Sheriff's plan all along! Swords clash and Robin and Archer soon join the melee. Isabella tries to stab Robin but Guy saves him – only to be run through by Vasey. As Guy lies dying, Robin realises he's been cut, and Isabella's dagger is coated with poison!

Back in the castle, Tuck has prepared barrels of Byzantine fire and a weakened Robin lays a trap. He orders his men into the tunnel as Vasey's soldiers pour through the castle gates and, once outside, Robin sends a flaming arrow through a castle window and into one of the barrels. The huge explosion rips Nottingham castle apart, the giant stone towers collapsing onto Isabella, Vasey and his army.

But amid the outlaws' celebrations, Tuck reveals that Robin has been poisoned. The outlaw leader says his farewells, walks alone into the forest and, as he lays dying beneath an oak tree, Robin watches as his beloved Marion walks towards him and then leads him away for ever...

*Last in the series*