During the fall of Shanghai in 1940, Lin Zhao, an apprentice in a tailor shop, became involved in the underground party intelligence network after his father and his contact, Lao Zhou, died one after another. He relied on half a minute of Ginkgo leaves with codes and a blood-stained code book. Under the hunt of the Japanese army, she shuttled through dark alleys, using cheongsam patches, watch parts, lipstick films and other covert carriers to transmit information, and gradually uncovered a code system intertwined with gears and ginkgo trees - this was not only the "code" woven by her comrades with their lives, but also the fate of the mysterious man rescued by her father seven years ago and her fate.
