"The Stoat" begins and ends with a passage involving a stoat (a wild animal related to the weasel) that attacked a rabbit. Most of the story concerns the narrator, a young man, and his widower father, who is looking for companionship and possibly marriage. The difficulties of finding love is the primary theme, and the relation between amorous pursuits and predatory behavior also figures significantly.
The father places a personal ad (as the story is set in pre-internet times) looking for a woman with similar interests and intentions. The narrator is soon astonished at the large number of responses his dad, self-described as "teacher, fifty-two," receives.
Much of the action involves the father's dating and courtship, centering on a certain Miss McCabe. One day the son meets her, finding her "frail and nervous" and "waif-like." He suspects that she is "in love with being in love" and as she is (in his eyes) "old," that she is "settling" on his dad.
It later develops that her frailty is associated with a heart condition, and she suffers a heart attack at the hotel where she is staying. The father cannot handle it. He abruptly decides to leave the nearby cottage where he was staying and end things with Miss McCabe. The son is left to deal with the fallout.
Throughout it seems that the son, a medical student, is closer to his uncle, a doctor, than to his own father. Anxious about his father's likely remarriage, he hesitates to share that with him. Although shocked by his father's sudden rejection of Miss McCabe because of her ill health, he is nonetheless relieved.
The ending, with its reprise of the stoat anecdote, is ambiguous. Who is the stoat, and who is the rabbit? Who is the predator, and who is the prey? From evidence in the story, the reader can make a case to identify either one with the son, father, or woman, or at different points, with all three.