Macbeth and Banquo, generals in the service of King Duncan of Scotland, are returning victorious from battle when they are hailed by three witches who prophesy that Macbeth will become Thane of Cawdor and then King of Scotland, whereas Banquo's descendants will be kings. The first part of the prophesy is soon fulfilled when Duncan rewards Macbeth's loyal service: encouraged by this, and playing on her husband's ambition, Lady Macbeth persuades him to murder Duncan while he is a guest at their castle. Malcolm and Donalbain, Duncan's sons, flee to England for safety. Macbeth, now king, has Banquo murdered in an attempt to secure his own position, but Banquo's ghost appears to him at a banquet. Macbeth visits the witches again. They warn him to beware of Macduff, a noble who has also fled to England, but assure him that he cannot be harmed by any man born of woman. Macbeth orders the murder of Macduff s wife and children. In England, Malcolm tests Macduff's loyalty and they then raise an army to march against Macbeth, but he, armed with the witches' prophecy, believes himself invincible. As his enemies draw nearer, Macbeth learns that his wife is dead. He faces Macduff in combat but when he learns Macduff was born by Caesarian section he realizes that he must face death. Malcolm is crowned King of Scotland.
In 1574, the 24 year old de Vere met Margaret, countess of Lennox and mother to Lord Darnley, the murdered second husband of Mary, Queen of Scots. She likely provided de Vere with access a manuscript in her family archives about the kings of Scotland. This manuscript is the main source for the play. It was not printed until the 19th century. The manuscript includes details, conversations and vignettes that can be found no where else and which include MacBeth's hallucinations to his paralysis at the site of a forest marching forward.
Mary Queen of Scots abandoned the Scottish throne in 1568, driven by a murder scandal in which Burghley's agents may have played a role. She was a legitimate heir to the English throne should Elizabeth die. As such, she was considered a threat to those around Elizabeth, who wanted her dead. In 1586, evidence was brought forward that she was plotting to overthrow Elizabeth. De Vere was one of 45 jurors who condemned Mary, Queen of Scots to death in October 1587. Elizabeth procrastinated in consenting to the execution until February 1588. The execution itself was botched; the executioner required to chops. Elizabeth disowned responsibility, laid responsibility with her secretary, and imprisoned him.
De Vere's view about the killing of a king was expressed in underlinings in his bible, and is summarized by MacDuff:
MACDUFF: Confusion now hath made his masterpiece:
Most sacrilegious murder hath broke ope
The Lord's anointed temple and stole thence
The life o' th' building.
As a member of the jury, de Vere was as much MacBeth as anyone. Mary was in England as a royal guest; under Scottish law, she was technically in England under a double trust. Macbeth notes this point of Scottish law:
MACBETH: He's here in double trust
First, as I am his kinsman and his subject,
Strong both against the deed; then, as his host,
Who should against his murderer shut the door,
Not bear the knife myself
De Vere was undoubtedly stating his personal views and guilt through MacBeth, when he said:
MACBETH: Had I but died an hour before this chance,
I had liv'd a blessed time; for from this instant
There's nothing serious in mortality:
All is but toys; renown and grace is dead,
The wine of life is drawn, and t he mere lees
Is left this vault to brag of.