Biographical story, based on life of Ino Tadataka, a Japanese measurer and cartographer. Ino Tadataka travelled the length and breadth of Japan on foot for 17 years from the age of 55 to perform his surveys. The accuracy of his maps also owed much to the fact that he was the first surveyor in Japan to combine measurements on the ground with observations of the heavens. Ino started the work as a private individual but earned the confidence of the Shogunate and it eventually turned into a national project. His maps were later used for many years as the foundation for maps made by modern survey techniques.

Sawatari Shusui was told about 7,000 ryo of buried gold by Osuke, who claimed to be a princess of the Fujiwara family. Shusui speculates that powerful people in the Date family and the shogunate are planning to overthrow the shogunate using buried gold and gets excited about a major national crisis. He gets separated from Osuke due to interference but with the help of his sister Kikuji and others he tracks down Osuke's whereabouts. He then realizes that Osuke is not from the Fujiwara family but is actually the daughter of Edo elder Itakura Shōken who has been confined under the pretext of an epidemic disease. Having promised to help Osuke, Shusui goes up to Edo Castle and advises shogun Tsunayoshi not to visit Nikkō Tōshō-gū Shrine which has been restored by Date family because "evil spirits are attached". However, Tsunayoshi is furious and orders him to stay under house arrest.

Sawatari Shusui saved Princess Hiroko of the Konoe family, who was about to be married to Tokugawa Tsunatoyo. However, Hiroko, a tomboy, disappears. As someone is after Hiroko's life, Shusui pursues her whereabouts... Meanwhile, Sasao Yoshinari and Shusui's sister, Kikuji, who were following Shusui, meet a young man and Kikuji is captivated by him, but they do not realize that he is Hiroko in disguise as a young man. Shusui is set to search for Hiroko with her attendant Orui, but that night they are attacked by a group of ninjas at their inn.

Adapted from Shusaku Endō's novel.