Left alone in the master's lair, a bound and gagged boy struggles against his restraints, his eyes darting nervously around the room filled with implements of pleasure and pain. His gaze falls on a table laden with urethral sounds, and his cock twitches in fearful anticipation. Using his tongue, he manages to pull a thick, curved sound towards him and, with some difficulty, positions it at the entrance of his urethra. With a deep breath, he pushes it in, wincing at the initial sting, but soon, the sensation morphs into a strange, pleasurable pressure. His cock hardens, and he begins to stroke it, the sound moving in and out of his urethra in rhythm with his hand, driving him towards a torturously intense orgasm.