Nobody appears in "Shut-in": no "I," no invalid, no face at a window. There are only hands, a house and some fish. The person exists in the title alone, and the poem's quiet trick is to make us infer them from what is left. Someone has been confined at home so long that their own body has become company.
The first stanza sets this up in two lines: "one hand owes money / to the other." "Hand" works twice here, as a body part and as a hand of cards. We can picture a solitary card game, one person betting against themselves. We can also picture two members of a household locked in a petty debt. Either way the joke is bleak. A debt passed between the two halves of one body can never really be collected, because whatever one hand wins, the other loses. The line break leaves "to the other" hanging for a beat, which makes the other hand feel like a separate person. The tone stays deadpan throughout. There is no punctuation and no capital letter, and the debt is stated as flatly as a fact about the weather.
The second stanza takes the familiar phrase "house of cards" and breaks it apart: "night falling / on the cards of their house." The cards now belong to the house, and the house is "theirs," which turns the two hands into a pair, almost an old married couple. The phrase also carries its usual meaning of fragility. Night falls, and the word "falling" quietly suggests that something built on cards will fall too. In gambling, "the house" is also the party that always wins, so the word may carry a trace of that rigged feeling. That is an inference, but it fits a poem about a game nobody can win. The darkness settles over the whole scene as the day runs out with nothing having happened.
The last stanza is the longest, and its image is the strangest: "their fish going / like nonsense words together / to and fro." It is the only part of the poem that moves, and all it does is move back and forth. "To and fro" is a worn-out idiom, which suits it. The phrase has been used so often that it has gone slightly dead, like the motion it describes. The simile "like nonsense words" is the poem's most inventive stroke. Fish in a tank dart and gulp silently, and the poet hears something like language that never lands anywhere. It could be the speech of someone with nobody to answer them. "Together" is the one word that hints at companionship, yet it is attached to nonsense. The fish are shut in as well, in a smaller house inside the house, and they give the shut-in a mirror.
The poem's construction is spare. It has seven lines in stanzas of two, two and three, so the poem lengthens slightly as it ends, as if trailing off. It has no rhyme and no punctuation, and the line breaks do the shaping instead. The grammar matters too. Only one finite verb appears in the whole poem, "owes." Everything else is a participle, "falling" and "going," which describe actions that never finish. Time doesn't advance here; it hangs. The sounds are soft and murmuring, with the nasal *n* and *m* of "money," "night," "nonsense" and "going" giving the poem a low, domestic hum.
What makes "Shut-in" worth reading is how much loneliness it fits into so few words, without ever saying the word. It doesn't tell us the person is sad or what keeps them indoors. It lets a pointless debt, a collapsing house of cards and a tank of aimless fish do that work. The humour is part of the effect, because the dry wit makes the situation harder to dismiss. By the end we understand that a mind left alone will invent a household out of whatever it can find, and that the household it invents is both comic and heartbreaking.