The Protestant Duke of Monmouth has landed in Dorset, determined to raise an army and wrest the throne from his Catholic uncle, James II.

Elam sets off with his sister, Perfect, to find their father and avoid the conflicts and passions of the Monmouth rebellion.

Joachim, Elam and Perfect are held by Royalist soldiers on the march. When they make camp, the children plan to free Joachim. Encountering two of Monmouth's men who wish to desert, Elam tries to inspire them to fight on.

The children seek refuge from the Royalists with Alice, an innkeeper in a village that supports the rebel cause - but danger stalks in the form of a merchant who plans to kidnap the children and hold them to ransom.

Elam and Perfect are still locked in the hovel while Bailey and Carrity wait for a chance to hand them to the Royalists. However, Joachim meets the travelling Players and together they arrive in the village, where innkeeper Alice has discovered Bailey's plot.

Still trying to reaching the Duke, Joachim, Elam and Perfect board a boat for a trip along the Bristol Channel to Bridgewater. Both the boatman and the weather turn against them.

Elam, Perfect and Joachim finally make it to Somerset but Joachim is arrested by the King's Dragoons when he is caught trying to steal some food.

Young Elam's claim to royal blood seems to be recognised when he is greeted as a prince on the road to Glastonbury - but it is only by a scheming merchant who plans to use the lad to gain favour with Monmouth.

The battle to decide the fate of the throne is imminent: the King's army camps on Sedgemoor while Monmouth plans a surprise attack. Meanwhile, Elam and Perfect decide to follow the assorted rebel forces as they march from Bridgewater.

The rival forces come together at last on Sedgemoor in a battle which will determine the future of the English crown once and for all.

After their disastrous rout at Sedgemoor, the battered remnants of Monmouth's rebels are forced to flee the wrath of the victorious Royalists. Elam and Perfect must not only save themselves but try to rescue the captured Joachim.

Elam finally confronts the man whom he believes to be his father. He finds that the Pretender is very unlike the man that he had imagined him to be.