Robin Hood is back stealing from the rich, until he is tricked by a woman who turns out to be the Sheriff's sister and one of his men turns against him.

In his first mission since discovering the devastating truth about operation Shah Mat, Robin launches an abortive raid on Nottingham Castle's new Strong Room. The Sheriff has stored all his Shah Mat funding in the medieval Fort Knox, but, before the Black Knights arrive to divide up the silver, he's preparing a final big deposit.

When a group of boys accidentally stumble on Gisborne's weapons-testing site, all but one is taken prisoner. The resourceful escapee, Daniel, is able to elude Gisborne's men and runs to Robin to raise the alarm.

The Sheriff and his sinister scientist, Joseph, are testing a chemical weapon on a street in Nottingham Town and blaming the ill effects on the Pestilence. But Dan Scarlett (Sean Murray), who is in town to visit his son Will, knows it is not the pestilence at all.

A horrified Robin realises that his plan to capture the Sheriff's spy, Henry of Lewes, has failed because he has a traitor in his gang. Fearing for Marian's safety in the castle, Robin sets about rooting out the turncoat. His only clue is supplied by Marian: the spy's meeting place is located at the Trip To Jerusalem Inn, where the traitor outlaw sells his secrets to Gisborne.

The Sheriff's Black Knights gather at the castle to attend a feast and declare their allegiance to Prince John by signing the Great Pact of Nottingham. With the outlaws disguised as entertainers, Robin infiltrates the castle to join forces with the only man who can stop them: former Sheriff Edward's old ally and Black Knight, the Sheriff of Winchester.

Robin is determined to get hold of the Great Pact of Nottingham, written proof of the Sheriff's treason. So when lovelorn knight John of York (John Hopkins) and his chest of silver pass by Robin and the gang, and the Knight begs the outlaws to take pity on him and save his girl, Robin formulates a plan.

Marian wakes up in Sherwood Forest on the first day of the rest of her life as an outlaw with Robin and his gang. Surprising everyone with a new energy and recklessness, however, she jeopardises the gang's mission to bring aid to Clun Village after it's ransacked by the Sheriff's men.

A mortally wounded messenger runs into the arms of Robin. It's clear that Gisborne and the Sheriff are hunting the man, and Robin must resort to desperate measures.

Tormented by Robin Hood, The Sheriff sleepwalks straight into Sherwood Forest. Unfortunately, he goes missing on the very day that Prince John's messenger, Jasper, arrives to check all is well in Nottingham. By the time Gisborne raises the alarm, Prince John's private army is already on its way, ready to raze Nottingham at sunset.

The Sheriff has turned Locksley into a garrison town, throwing its people out to make room for an army of vicious mercenaries. As Robin and the outlaws formulate a response plan to stop them, they are intercepted by three burly King's Guards, led by the fearsome Legrand who brings a vital message from King Richard.

Robin and the Outlaws arrive at a barn for Robin's birthday party, only to find that they are surrounded by The Sheriff's mercenaries and will not be let out alive. The Outlaws share their secrets with one another while the traitor, Allan A Dale, realizes that The Sheriff and Gisborne are heading to the Holy Land to kill the King.

Robin and the Outlaws, The Sheriff, Gisborne and Marian are now in the Holy Land. Robin warns the King of the impending threat to his life, but The Sheriff's cunning has prevailed and, instead of a heroes' welcome, Robin and the Outlaws are treated as traitors. Marian makes a final attempt to redeem Gisborne - if he kills The Sheriff, he will have everything he wants, including her.