It reaches its climax in the escape of Mary, Queen of Scots from Lochleven Castle leading to her defeat at the Battle of Langside and her final departure from Scotland.
He laid that aside to complete Ivanhoe, and by the time he resumed writing in November he realised he had sufficient material to make two three-volume novels.
There is no reason to suppose that Scott was involved with the novel again until the beginning of 1830 when he revised the text and added an introduction and notes for the 'Magnum' edition where it appeared as Volumes 20 and 21 in January and February 1831.
Ten years had passed since the final events of The Monastery, during which Halbert had been knighted for his services to the regent, and Lady Avenel had adopted Roland, whom her dog had saved from drowning.
The boy grew up petted by his mistress, but disliked by her chaplain and servants; and at length, having threatened to dirk the falconer, he was dismissed to seek his fortune.
She now introduced him to Catherine Seyton, and then accompanied him to the abbey, where the revels of some masqueraders were interrupted by the arrival of Sir Halbert on his way to Edinburgh, who attached the youth to his train.
On reaching the capital he aided Lord Seyton in a street fray, and was introduced to the Earl of Murray, who desired him to be ready to travel at short notice.
In company with Adam Woodcock he adjourned to an inn, and was entrusted by Henry Seyton (whom he believed to be Catherine in male attire) with a sword, which he was not to unsheath until commanded by his rightful sovereign.
He then learnt that he was to be attached to the household of Queen Mary, and accompanied Lord Lindesay to the castle of Lochleven, situated on an island, where he found Catherine in attendance on her, and was present when, in compliance with a note contained in his sword-sheath, she signed her abdication at the behest of the Secret Council.
After a lapse of several months, during which Henderson attempted to convert him, Roland learnt from Catherine that Father Ambrose had been evicted from his monastery, and he pledged himself, for her sake, to assist the imprisoned queen in recovering her freedom.
A plan of escape arranged by George Douglas having failed through the vigilance of the Lady of Lochleven, Roland undertook to forge a false set of keys, and the abbot arrived disguised as a man-at-arms sent by Sir William to take part in guarding the castle.
At midnight the garden gate was unlocked, a boat was in waiting, Henry Seyton came forward, and the queen, with all her adherents, was safely afloat, when the alarm was given.
Roland, however, had run back, ere they started, to turn the locks on their jailers, and, until they were out of reach of musketry, George Douglas protected Mary by placing himself before her.
The next morning, as the queen was endeavouring to make peace between Roland and Henry Seyton, who treated the page as a churl, his grandmother emerged from a recess and declared him to be the son of Julian Avenel, who was killed in the battle with Sir John Foster; Lord Seyton also recognised him, and insisted that his son should shake hands with him.
Supported by a considerable number of adherents in battle array, and accompanied by the abbot, the royal party moved onwards for Dumbarton, where help from France was expected.
The queen stood near a yew tree, guarded by her devoted admirer George Douglas in close armour, while her page pushed forward to watch the conflict.
It had lasted nearly an hour, when Sir Halbert attacked the flank of Mary's supporters, and they were completely routed, Henry Seyton was killed, and Douglas, who was mortally wounded, expired without withdrawing his eyes from her face.
Hopeless of further aid, the queen adopted the fatal resolution of trusting to Elizabeth's mercy, and, having bid adieu to her followers, took ship for England.
Roland soon afterwards succeeded in obtaining proofs of his claim as the heir of Avenel, and was married to Catherine on her return from two years residence with her unhappy mistress.
(principal characters in bold; Douglas family relationships as in the Edinburgh Edition) Introductory Epistle: The Author of Waverley writes to Captain Clutterbuck apologising for cutting so much from the Benedictine manuscript entrusted to his care: notably the White Lady has been excised, as has much enthusiastic Catholicism associated with Magdalen Graeme and the Abbot, making the title less apposite than originally intended.
Volume One Ch.1: The stag-hound Wolf rescues a boy [Roland Græme] from the lake at Avenel, but both dog and the preacher Warden disapprove of the Lady's affection for the child.
9: With some reluctance Roland promises Magdalen to be obedient to the Catholic cause, having been secretly instructed in the faith at Avenel by Fr Ambrose (Edward Glendinning).
3 (18): At Holyrood, Michael Wing-the-Wind fills Adam in on the political situation before conducting Roland to deliver a letter from Sir Halbert to Moray, who is impressed by his spirit.
George Douglas warns him against attempting to leave the castle and reveals by his manner that he is attracted by Catherine, who proceeds to re-dedicate Roland to the Catholic cause.
1 (27): A[n apparent] maiden, who Roland takes to be Catherine [in fact, Henry in disguise], is brought before Lundin for hitting a jester at a rustic theatrical performance.
Roland and Catherine make Lady Lochleven believe Mary has drunk the poison, but Magdalen arrives with Lundin and it becomes clear that this is not the case, and in any event the liquid was harmless.
7 (33): Resigned to his fate, Dryfesdale undertakes to deliver a message from Lady Lochleven to her son Moray advocating his death, but on the way he is stabbed by Henry Seyton: George Douglas arrives to witness his last moments.
Magdalen reveals Roland's parentage, but Henry Seyton, taking him to be illegitimate, continues to reject his aspiration to Catherine's hand.
12 (38): At Dundrennan abbey, Ambrose and Roland encounter Boniface, still a gardener, who tells how Julian Avenel's marriage certificate had been taken from him by troopers under Sir Halbert.
Reviewers generally welcomed The Abbot as a return to form after The Monastery (the absence of the White Lady being particularly noted), and some even saw the novel as ranking with Waverley.