ACT I At Smith the armourer's workshop.

Workmen are busy at the forge in Smith the gunsmith's workshop. Smith dismisses them for the Carnival and, left alone, falls to thinking of the coquettish Catherine he would make his Valentine [fiancée) if she would only consent at last. Pursued by enterprising young noblemen, Mab, the Queen of the Gypsies, seeks refuge in Smith's workshop and to thank him, tells his fortune; but she has to hide in the adjoining room to avoid arousing the jealousy of Catherine who happens to arrive just then, followed by her father Glover, the glove-maker, and one of his apprentices, Ralph, The three invite themselves to dinner at Smith's, Catherine sings of the joys of winter then Glover and Ralph withdraw in search of the meal, deliberately leaving the lovers alone together. Smith gives his beloved a rose in enamelled gold, a little ahead of Saint Valentine's Day. Catherine accepts but soon finds an opportunity to infuriate her suitor when a stranger who has been following her enters and asks Smith to straighten out the blade of his dagger. He is the Duke of Rothesay and takes advantage of the situation to court the coquette who pretends to be flattered. Smith, totally exasperated, is about to knock the Duke over the head when Mab emerges from her hiding place to protect her flighty lover from harm. Taken aback, Catherine then wants to withdraw in favour of the person she believes is her rival. Whereupon Glover arrives and is nonplussed by the situation but takes this opportunity to request an audience with the Duke for the following day. In her fury, Catherine throws away the rose; Mab picks it up intending to return it to her later and the curtain falls amidst general contusion.

ACT II A public square.

Later on in the evening Glover and a few fellow citizens are doing their round. They flee at the first strange noise - the cries of a band of revellers celebrating carnival that their leader [none other than the Duke] has gathered beneath Catherine's windows-After having a huge cup brought to him, he presses his friends to drink by singing a song, Mab joins them and is asked to dance; she complies and by way of a thank-you, the Duke asks a service of her: to bring Catherine, masked, to the feast he is to give that evening at his palace. Instead of showing her resentment Mab initially laughs at the Duke's fickleness, then agrees, swearing revenge. The stage empties and Smith enters to sing a serenade to his beloved, unsuccessfully. A passing workman tries to entice him to a pub but he decides to stay put until dawn. Midnight strikes. Ralph arrives, drunk and proclaiming his despair at not being loved. The Duke's steward is asking him where Catherine Glover's dwelling is when a lady looking like her gets into a litter. Coming back to his senses Ralph sends Smith in pursuit of the person he has taken for his master's daughter and when the real Catherine decides to reply to her lover's serenade, the latter is already far away.

ACT III Evening festivities at the Palace.

The Duke, as lucky in love as he is in gambling, announces to his friends the arrival of his latest conquest. A lady does indeed appear but will unmask only for him. Alone with the Duke, Mab takes off her domino once the lights are off and soon flees, having bestowed on her lover nothing more than Catherine's enamelled rose she had been wearing on her bodice. When Smith arrives, the room is deserted: he laments Catherine's infidelity. Time flies and the morning audience is due any moment. Smith hides as the Duke receives Glover who has come to invite him to his daughter's approaching wedding. The Duke is surprised and Smith, emerging from his hiding place, accuses Catherine of having dishonoured him, She protests and he is about to forgive her when he catches sight of the enamelled rose on the Duke's doublet, confirming his worst suspicions.

ACT IV A few hours later, in a wild spot.

(First tableau)

A group of craftsmen is trying to convince Smith of Catherine's innocence. Ralph champions her and agrees to meet Smith in a duel for God's judgement. Left alone Smith receives a visit from a grief-stricken Catherine who has come to bid him farewell- Smith replies that he will let himself be killed in order to restore her honour to her. In the meantime, Saint Valentine's Day is being celebrated on the main square

(Second tableau)

Mab, looking for Catherine to tell her that Smith is alive and well [the combat having been cancelled through the Duke's intervention] learns from Glover that his daughter has gone mad. The ballade she sings provides instant proof of this. The Gipsy decides to attempt to restore her tc her senses by creating a psychological shock. Mab, appearing at the window in Catherine's clothes, answering Smith's serenade:- Confronted with this Imposture Catherine recovers her identity and swoons in the arms of her beloved. On awaking she thinks it has all been but a dream.