"Goblin Market" is about two close sisters, Laura and Lizzie, as well as the goblins to whom the title refers.
Although the sisters seem to be quite young, they live by themselves in a house, and are accustomed to draw water every evening from a stream. As the poem begins, twilight is falling, and as usual, the sisters hear the calls from the goblin merchants, who sell fruits in fantastic abundance, variety and savour. On this evening, Laura lingers at the stream after her sister has left for home, intrigued by the goblins' strange manner and appearance. (Rossetti hints that the "goblin men" resemble animals for example, having faces like wombats or cats, and possessing tails.) Longing for the goblin fruits but having no money, the impulsive Laura offers a lock of her hair and "a tear more rare than pearl."
Laura gorges on the delicious fruit in a sort of bacchic frenzy, then once she is finished, after picking up one of the seeds, returns home in an ecstatic trance. Lizzie, waiting at home, and "full of wise upbraidings," reminds Laura about the cautionary tale of Jeanie, another girl, who, having likewise partaken of the goblins' fruits, died just at the beginning of winter, after a long and pathetic decline. Strangely, no grass grows over Jeanie's grave. Laura dismisses her sister's worries, and says she shall return to the goblins the next night and return with more fruits for herself and Lizzie. That night, the sisters go to sleep in their shared bed.
The next day, as Laura and Lizzie go about their work in the house, Laura dreamily longs for the coming evening's meeting with the goblins. However, at the stream that evening, as she strains to hear the usual goblin chants and cries, Laura discovers to her horror that, although Lizzie still hears the goblins' voices, she cannot.
Unable to buy more of the forbidden fruit, and sickening for the lack of it, Laura falls into a slow physical deterioration and depression. As winter approaches, she withers away, aging at an unnatural rate and physically unable to do her accustomed household work. One day she remembers the saved seed and plants it, but nothing grows.
Months pass, and Lizzie realizes that Laura is on the verge of death. Lizzie resolves to visit the goblins to buy some of their fruit, hoping to soothe Laura's pain. Carrying a silver penny, Lizzie goes down to the brook and is greeted in a friendly way by the goblins, who invite her to sit and dine with them. When they realize, however, that the Lizzie means to pay with mere silver to buy the goblin-fruits to help another person, they turn upon the girl. The goblins viciously pummel and assault Lizzie, and try to feed her their fruits by force. In the process, they drench the brave girl in fruit juice and pulp but Lizzie ingests none of the goblin fruit.
Lizzie escapes and runs home, hoping that Laura will eat and drink the pulp and juice from her body. Her dying sister does so, but the taste of the fruit repulses her rather than satisfies her hunger. Laura then undergoes a violent transformation of such intensity that her life seems to hang in the balance.
By morning, however, Laura is restored, emotionally, physically, and mentally. The last stanza attests that both Laura and Lizzie live to tell their children of the evils of the goblins' fruits and the powers of sisterly love.
Output: What do the goblins do when they discover Lizzie is trying to buy goblin fruit to help her sister?