Baz Luhrman’s film of Romeo and Juliet with Clare Danes and Leonardo DiCaprio prompted Sharman Macdonald’s 13-year-old daughter Keira Knightley to tell her to write play about Rosaline. Undoubtedly Rosaline appears on stage in Romeo and Juliet and at the Capulet’s party but she is not in the cast list and, although Romeo is besotted with her in Act I Scene 1, she is only mentioned twice. The daughter's demand together with the film's electrifying music and the tough sinewy style that made the Shakespearean language a dialect that young people could use, led Sharman Macdonald to speculate on how she could explore what happened in the days immediately after the deaths of Romeo and Juliet.

I decided to use the text by Brooke that Shakespeare used as his source. After Juliet is a kind of doggerel because it has vitality and there is the potential for mischief in it. It's allowed to make a fool of itself occasionally. It gave me the freedom to leap off from the play and the film. Increasingly I want to write with music and an integral part of After Juliet is the music composed by Caleb Knightley and Adrian Howgate.

In After Juliet the embargo on weapons is being enforced but the feud between the young Capulets and Montagues is simmering. Rosaline, convinced that there should be fighting, raids the tomb to get the only swords available. Implacable Valentine does the same so that when the new Prince of Cats is elected, ‘the days will breathe again.’ Rosaline forces the Capulets to choose between peace and war. After she is elected Princess of Cats, she fights Valentine with total conviction. However, she is unable to sustain her animosity when Benvolio takes up the fight and simply challenges her to kill him. She is not exactly enthusiastic in response to Benvolio’s passion but at least she takes his hand and promises that, in the spring, she will wear that special green dress that he liked, pale, pale green.

Rosaline is eaten up by unrequited love for Romeo and the conviction that Juliet was responsible for all the deaths and for the fate of the four people who are on trial for their lives. She's down a long way and has a journey to go but she is always fighting. She is a very feisty lady. There is hope that she is going to come through that deep despair of adolescence is to a place where there is light and life. In the end she is redeemed by Benvolio’s innocent love.

Aftershocks rock this society which could be in Verona, Edinburgh, Dublin, New York or Liverpool. Wherever it is, there is a deliberate tension created between the clear references to the original story and such things as hand- rolled cigarettes, chrome toasters, a gleaming electric fan and a fridge. In this setting After Juliet looks at how justice is meted out in the trial of those held responsible for the deaths of Romeo and Juliet. The friar goes into self-imposed solitude and contemplation; Angelica, the nurse, is spared but exiled; Peter, because he simply obeyed orders, is set free; but the apothecary is hanged by the throat. This is strange justice, law meted out by the rich as if riches bear witness to virtue. In this timeless society even honourable men need a scapegoat and, although the young people can see that the apothecary was only supplying their needs and was seduced by Romeo’s ducats, he still has to hang.

Despite convincing characterisations and some excellent exchanges between Benvolio and Valentine, the women dominate the play. Rosaline is scorned, vindictive, assertive and single-minded but she is also a fighter with a lightness and a sense of humour. Bianca, on the other hand, is a visionary, otherworldly, magical, holding the balance of the peace in her hands. Helena is the carer, the surrogate mother who expresses some of the frustrations that a carer feels while Rhona, the outsider from Glasgow, is seen as a threat.

Because this is a short piece, many issues are touched on but not fully explored. The death penalty, the shadow of Northern Ireland and the death of Princess Diana are there for the discerning. However, love, death, and revenge are central and come together in the feud that persists despite the decrees of the authorities and the emotional involvement of the characters. The stage directions indicate that Rosaline is not close to Benvolio although she does not take her hand away from his. Alice attacks Petruccio and is subdued when he kisses her. The drummer tick ticks with his drum sticks. The flute plays and two Capulets and one Montague are left on stage. Valentine unsheathes his sword, Gianni accepts the challenge. The drummer points. The flute trills and falls silent. The men prepare to scratch the itch once more.

West Side Story, which I love, and Romeo and Juliet end on a note of sad optimism. The impression given is that things will change. If only it were that easy. Things don't change because two people have died. There is no death that puts a stop to anything. If the mind is emptied of the preoccupation that has been its obsession, what does the mind turn to? Where does it go? My conclusion is that the itch is still there and, because you can scratch it, you do. There are themes in After Juliet that are germane to how we live today and there is something for performers to bite on. I was profoundly changed by seeing West Side Story when I was young and now I never write without wanting to affect people in some way. I hope that After Juliet opens up discussion. I hope the roughness and rawness of the play will keep people talking, and maybe even laughing, for at least a couple of minutes after the curtain comes down.