On a summer evening, Klausner hurries back to his workshop to continue tinkering with a small black box full of complex wires. He works excitedly on the machine with intense focus for some time before being interrupted by a visit from the town physician, Scott. After Klausner distractedly dismisses the man’s concern for his sore throat, the Doctor soon takes notice of the object of Klausner’s attention and questions him about its purpose, whereupon Klausner launches into an emphatic discussion of his research into translating pitches too low or high for the human ear into audible levels. The Doctor is amused but thinks the idea is implausible. As he leaves the man to his work, the Doctor silently questions Klausner’s mental state.
After spending some more time tinkering with the machine and muttering to himself, Klausner brings his machine to working order and decides to test it in his garden. He has the feeling that he shouldn’t be trying this experiment—that he is veering into “forbidden territory, a dangerous ultrasonic region where ears had never been before and had no right to be.” Despite this feeling, Klausner presses on. When he slides on his headphones, he hears a terrifying shriek, but sees no possible source except for his neighbor, Mrs. Saunders, who is peacefully tending to her roses. He soon realizes the noises correspond with the cutting of the roses, and in horror deduces that plants emit small screams of pain inaudible to human ears. He frantically alerts Mrs. Saunders to this discovery, greatly worrying her in the process—she has always found him a bit odd, but now she is certain that he is outright mad. Klausner leans over the fence and whispers frantically to her about his discovery, Mrs. Saunders decides to dart back into the house for her own safety.
The next morning, unconvinced of the true nature behind the sound the roses made (whether it was truly a cry of pain or some other sensation or feeling humans don’t have a word for), Klausner sets out to test his hypothesis further by taking an axe to a tree, which results in him hearing a prolonged growl of agony. Now fully convinced, the terrified Klausner breaks down, apologizing to the tree for hurting it and attempting to heal its wound.
On the heels of this discovery, Klausner calls the Doctor and begs him to come quickly, even though it’s only 6:30 a.m. The Doctor senses something frantic and even mad in Klausner’s voice and agrees to head over promptly. While waiting for the Doctor, Klausner dwells on the implications of this new knowledge, considering what humans would feel if someone took an axe to them and wondering which fruits and vegetables are free to eat without guilt.
The Doctor arrives and Klausner brings him to the tree, giving him the machine’s earphones so he may hear the tree’s cry as well. When Klausner goes to strike the tree this time, however, he feels a shifting of the ground beneath him and a branch falls from above after the axe hits, destroying his machine and nearly hitting both him and the Doctor. When questioned, the Doctor denies having heard anything in the earphones—after all, he ripped them off of his ears and began to ran away the second he saw the tree tipping over—and Klausner interprets the man’s skittish demeanor as a sign that he may be holding back the truth. He firmly directs the Doctor to dress the tree’s wound. The Doctor, now in fear of a possible violent outburst from the man, complies, assuring him he will come back to tend to the tree again the next day if need be before gently leading him back home.
