During an ambush against Guy of Gisborne, Robin Hood and the outlaws discover a baby boy abandoned in the forest.
Later, Roy is brought before the Sheriff of Nottingham and given an ultimatum: kill Robin Hood, or watch his own mother hang.
Robin is shot in the arm with an arrow while feeding the villagers, but he and Roy escape and are then joined by the rest of the outlaws.
After Robin leaves, the Sheriff orders Marian to be punished for feeding the villagers by having her hair cut on the public gallows.
The Sheriff holds an archery competition with a silver arrow as the prize in hope of finding Robin, but the outlaws have other plans.
Robin intends to rob everything back once it reaches the castle, by using York's silver to locate where the Sheriff's treasure - including the Pact - is hidden.
Whilst Marian tends to Edward in the dungeons, she overhears Allan giving all of the outlaws' secret entrances and escape routes away.
As Edward and the gang flee, the Canon of Birkley steps in their path and threatens to kill Robin unless he hands over the Pact.
When Marian sees her father's body, Gisbourne tries to comfort her in her distress, telling her that his feelings for her are stronger than ever, then moves to kiss her but she turns away.
The Sheriff, Gisborne and Marian arrive in the Holy Land to put the deadly Shah Mat operation into action.
Fearing this may be their last chance, Robin and Marian begin to exchange wedding vows before Carter appears on the horizon to rescue them.
In Locksley, Robin has an epic battle with Gisborne to avenge Marian's murder, with both determined to fight to the death.
Tuck finds Robin barely alive, and revives him, believing he's the only man who can unite the people of England and destroy the tyrannical reign of the Sheriff, Gisborne and Prince John.
Meanwhile, the Sheriff learns Prince John will fire him for failing to kill King Richard - unless he pays a thousand crowns a month.
Kate (Joanne Froggatt), a village girl from Locksley, tries to help the outlaws to rescue her captured brother, but her heroics have devastating consequences.
The Sheriff turns the heat up on Robin and his gang by forcing the Abbot of Kirklees to accuse the outlaws of stealing from the church.
Pitching in all their resources and skills, the gang plans to trade Edmund, Rufus' son, for Allan and Kate.
Meanwhile, Gisborne's estranged sister, Isabella (Lara Pulver) is rescued by Robin in Sherwood Forest, who is unaware of the siblings' relation.
Prince John (Toby Stephens) pays a long-awaited visit to Nottingham, and he is out to make trouble, longing for the coveted title of King.
The Royal Keeper of the Keys and Robin's former mentor, Lord Sheridan announces that King Richard has been killed in battle.
The gang are shocked when Robin announces that Gisborne is joining their fight against Isabella, but can their uneasy truce survive?
Unfortunately, Isabella's machinations turn the gang against each other when they need unity most, and unknown to all, the previous Sheriff is back for his vengeance, and attacks the city with a vast and terrible army.