The forest encounter begins while Arthur is hunting near Carlisle. He has killed a hart and is occupied with it when an armed knight approaches. Arthur wears hunting clothes rather than armour, leaving him at a serious disadvantage. Gromer identifies himself and says that the king has wrongfully given his lands to Gawain. This is his accusation; the poem does not supply a charter or an independent account settling the ownership dispute. Arthur appeals to the dishonour of killing a defenceless man and offers to amend what is wrong. Gromer instead uses his advantage to impose a dangerous agreement.

Arthur must swear on Gromer's sword to return alone at the end of twelve months. Unless he can say what women most desire, he will lose his head. Back at Carlisle, the king eventually shares his predicament with Gawain. They travel separately, gathering answers about wealth, affection, marriage, admiration and other desires, but cannot be certain which will satisfy the challenger. The threat therefore requires something that military strength cannot provide. Gromer remains absent through much of this search, yet the obligation he has imposed shapes every decision made by the king and his nephew.

The decisive encounter is with Dame Ragnelle, who knows Arthur's danger and offers the answer on condition that Gawain marry her. Arthur does not bind his nephew without consulting him. Gawain accepts the bargain, and Ragnelle reveals the answer concerning women's sovereignty. When Arthur returns, Gromer rejects the collected alternatives but recognises this final reply as the answer his sister would have supplied. He is angry with her, yet the king has fulfilled the condition and must be allowed to leave. The poem's riddle is answered through a woman's knowledge rather than through Gromer's sword or Arthur's authority.

Gawain then keeps his promise to Ragnelle. His willingness to let her choose between the forms offered by her enchantment gives practical force to the answer about sovereignty, and the spell is broken. Afterwards she asks Arthur to be a good lord to Gromer despite his offence, and Arthur agrees for her sake. This reconciliation is explicit, but the poem does not describe a separate ceremony installing Gromer at the Round Table. Readings that make the marriage a solution to an inheritance dispute are interpretations of the land grievance and family relationships, not a detailed transfer of estates narrated in the wedding scene.

Malory names Sir Gromore Somir Joure among the knights gathered by Agravain and Mordred at Carlisle to catch Lancelot with Guinevere. The attempted arrest becomes a fight: Lancelot kills Colgrevance, takes his armour and overcomes the other attackers, while the wounded Mordred escapes. Gromore is among those killed. The textual form Sir Gromoreson is also recorded in the Winchester manuscript, as noted by the modern editor of the Ragnelle poem. These links justify discussing the related names together, but they do not turn Malory's brief appearance into an explicit sequel to the wedding. Gromer survives in the tradition through contrasting scenes of coercion, reconciliation and conflict within Arthur's fellowship.