When Robin Hood, Gisborne and the outlaws intercept one of Isabella’s messengers with a missive to Prince John there is both good and bad news, in tonight’s penultimate episode in the current series of the medieval drama.

The outlaws rejoice when they learn that King Richard is a month away from home and rallying troops to fight his brother’s attempt to usurp him. But the gang are appalled when they discover that Isabella is confiscating food and snatching men from nearby villages to raise a force of some 300 militia for Prince John’s side. Her next target is Locksley.

Robin, meanwhile, pledges that England will never be slaves to Prince John and he and the gang rush to Locksley where the villagers are under siege. Isabella’s right-hand henchman, Blamire, and his thugs are trying to kidnap the male villagers. There’s a pitched battle and the gallant outlaws succeed in saving the men of Locksley and then give them sanctuary in Sherwood Forest.

Elsewhere, the ever-opportunistic Archer seeks out Isabella, informs her of their kinship and propositions her: her power and his skills could make them an unstoppable alliance. She’s not impressed, however, and has Blamire promptly throw Archer in the dungeons. But has she finally met her match?

In the woods, Tuck preaches that the Lord helps those who help themselves, while Robin worries they are outnumbered and hopelessly ill-equipped to take on the might of Prince John and his allies.

But then the most audacious scheme is implemented when Gisborne reveals a secret way into Nottingham Castle – which might just mean that it can be seized and held for King Richard. The stakes have never been higher and there will be gains and tragic losses on both sides before the battle can be won.

Saturday 20 June
6.45-7.30pm BBC ONE