The action occurs between 2 and 29 December 1170, chronicling the days leading up to the martyrdom of Thomas Becket following his absence of seven years in France. Becket's internal struggle is the main focus of the play.
The book is divided into two parts. Part one takes place in the Archbishop Thomas Becket's hall on 2 December 1170. The play begins with a Chorus singing, foreshadowing the coming violence. The Chorus is a key part of the drama, with its voice changing and developing during the play, offering comments about the action and providing a link between the audience and the characters and action, as in Greek drama. Three priests are present, and they reflect on the absence of Becket and the rise of temporal power. A herald announces Becket’s arrival. Becket is immediately reflective about his coming martyrdom, which he embraces, and which is understood to be a sign of his own selfishness—his fatal weakness. The tempters arrive, three of whom parallel the Temptations of Christ.
The first tempter offers the prospect of physical safety.
- Take a friend's advice. Leave well alone,
- Or your goose may be cooked and eaten to the bone.
The second offers power, riches and fame in serving the King.
- To set down the great, protect the poor,
- Beneath the throne of God can man do more?
The third tempter suggests a coalition with the barons and a chance to resist the King.
- For us, Church favour would be an advantage,
- Blessing of Pope powerful protection
- In the fight for liberty. You, my Lord,
- In being with us, would fight a good stroke
Finally, a fourth tempter urges him to seek the glory of martyrdom.
- You hold the keys of heaven and hell.
- Power to bind and loose : bind, Thomas, bind,
- King and bishop under your heel.
- King, emperor, bishop, baron, king:
Becket responds to all of the tempters and specifically addresses the immoral suggestions of the fourth tempter at the end of the first act:
- Now is my way clear, now is the meaning plain:
- Temptation shall not come in this kind again.
- The last temptation is the greatest treason:
- To do the right deed for the wrong reason.
The Interlude of the play is a sermon given by Becket on Christmas morning 1170. It is about the strange contradiction that Christmas is a day both of mourning and rejoicing, which Christians also do for martyrs. He announces at the end of his sermon, "it is possible that in a short time you may have yet another martyr". We see in the sermon something of Becket's ultimate peace of mind, as he elects not to seek sainthood, but to accept his death as inevitable and part of a better whole.
Part II of the play takes place in the Archbishop's Hall and in the Cathedral, 29 December 1170. Four knights arrive with "Urgent business" from the king. These knights had heard the king speak of his frustration with Becket, and had interpreted this as an order to kill Becket. They accuse him of betrayal, and he claims to be loyal. He tells them to accuse him in public, and they make to attack him, but priests intervene. The priests insist that he leave and protect himself, but he refuses. The knights leave and Becket again says he is ready to die. The chorus sings that they knew this conflict was coming, that it had long been in the fabric of their lives, both temporal and spiritual. The chorus again reflects on the coming devastation. Thomas is taken to the Cathedral, where the knights break in and kill him. The chorus laments: “Clean the air! Clean the sky!", and "The land is foul, the water is foul, our beasts and ourselves defiled with blood." At the close of the play, the knights step up, address the audience, and defend their actions. The murder was all right and for the best: it was in the right spirit, sober, and justified so that the church's power would not undermine stability and state power.