The percussionist stands up. "Every radio operator has a distinctive style of keying—we call it his fist. With a bit of practice, our Y Service people can recognize different German operators by their fists—we can tell when one of them has been transferred to a different unit, for example." He nods in the direction of the albino woman. "Miss Lord has intercepted numerous messages from U-691, and is familiar with the fist of that boat’s radio operator. Furthermore, we now have a wire recording of U-691’s most recent transmission, which she and I have been studying intensively." The percussionist draws a deep breath and screws his courage up before saying, "We are confident that I can forge U-691’s fist."