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In 1983 Beijing, Shu Xiaocun bonds with homing pigeons "Marathon" and "Cinderella" through Yunzi, their owner. Enlisting as a signal soldier, he deploys the pigeons to relay orders at a remote outpost. After sacrificing himself to save a comrade, his red-star badge is sent via pigeon to Yunzi—sealing their unspoken camaraderie beyond life and duty.