Setting: London in 1982
Act I
In the first scene the coldly witty Max correctly accuses his distant and travelling wife, Charlotte, of infidelity. She leaves embarrassed and angry.
The second scene appears to follow directly after the first, but Charlotte's personality has changed completely, and she is now married to a playwright named Henry. Gradually the audience realises that Charlotte is an actress, and the first scene was her performance in a play that Henry, her husband, wrote. She is unhappy with the play, believing that Henry gives short shrift to the female character in order to show off his own wit through the mouth of Max.
Max and his wife Annie drop by for a visit to Charlotte and Henry. Without the benefit of Henry's dialogue, Max turns out to be a likeable but negligible fellow, and Annie is, according to the script, "very much like the woman Charlotte has ceased to be." Annie is a devoted activist on behalf of an imprisoned vandal, Brodie, and Henry mocks her as a sentimental do-gooder, giving offence to Max. But when Annie and Henry are left alone, it's revealed that their fight was also a performance: they are having an affair, and she agrees to meet him later on the pretext of visiting Brodie in prison.
Max discovers the affair, and Annie leaves him to be with Henry. Soon, Henry is reduced to writing television scripts in order to pay alimony to Charlotte. He struggles to write a play about his love for Annie, but finds it difficult to find the right language to express sincere emotion: he is more comfortable with comedy.
Act II
Two years later, Henry's play about Annie remains unwritten. Annie asks him to ghost-write a play by the prisoner Brodie, whom she continues to visit. Brodie's incoherent anarchist politics, anti-intellectualism , and lack of ability for writing are the antithesis of everything Henry values. Annie discounts this in favour of the intention behind the writing. Henry defends the importance of beauty in language and skill in writing using an analogy with a cricket bat: good writing is like hitting a ball with a cricket bat (ie something that has been carefully designed to hit balls in the best manner possible); bad writing is like hitting it with a plank of wood (ie, something that has the same composition as a cricket bat, and bears it some resemblance, but is ultimately random and inferior).
When Annie is cast in a production of 'Tis Pity She's a Whore in Glasgow, she must be away from Henry for some time, and Henry visits Charlotte and their daughter Debbie. The teenage Debbie declares that monogamy is a thing of the past, a form of colonisation. Henry gently cautions the girl against his own vice of making clever phrases for their own sake, but he is shaken by her cynicism nevertheless. For her part, Charlotte breezily admits to multiple affairs during their marriage, and tells him that his affair with Annie only caused trouble because he treated it romantically instead of as a source of fun.
Henry returns home in a frenzy of jealousy and ransacks his and Annie's apartment searching for evidence of infidelity. His confrontation with Annie echoes the scene from the play he wrote that was performed in the first act of The Real Thing , but Annie has more to say than his imaginary wife did. She admits that she is having an affair with her young co-star Billy, but refuses to either give Billy up or leave Henry: both romances have a moral claim on her, and Henry will just have to accept it. With pain, he does.
As if their relationship were not under enough strain, Brodie is released from prison and stops by for a visit. He turns out to be a prize oaf, with all of Henry's arrogance and elitism, but none of the genuine skill or eloquence to back it up. At last, Annie pushes a bowl of dip in his face and throws him out of the house, and peace between her and Henry is restored. The play ends with a phone call from Max, who tells Henry that he has become engaged.
