The speaker and a neighbor are chatting about a rat snake that lives in and around the walnut tree, even tracing its route in the speaker's mind: up the trunk, along a branch, onto the roof, into a squirrel hole above the kitchen. They find a shed skin caught on a thorn, and the speaker jokes that its owner won't be back for it. Then the neighbor looks up, and the snake is right there.
The mood shifts from casual, amused talk to a hushed, slightly unnerved attention. The speaker seems startled, and the mild insult "son of a bitch" reads as a mix of surprise and grudging respect. The snake is compared to a tongue "with bad news," which makes its stillness feel loaded, as if it knows something. The poem ends with the snake imagined as a "limbless dragon" with a flickering "Y of flame," so an ordinary backyard animal becomes something mythic and a little dangerous.