Set in early 17th-century Japan, shipwrecked English navigator John Blackthorne finds intrigue and culture shock in a feudal society that puts a premium on honor. A rival Lord sentences Blackthorne to death.

After Lord Toronaga rescues Blackthorn from prison, he enlists him as his aide and names him, 'Anjin-san'. Mariko is directed to tutor Anjin-san in the language and customs of Japan.

Blackthorne and Mariko begin a romance; Toronaga continues to build his army for a battle with Ishido. Anjin-san proves his mettle during an earthquake and is honored by Toranaga for bravery. Mariko's husband Buntaro, arrives in Anjiro.

Anjin-san's assimilation of Japanese ways is evident in his exemplary conduct. Toranaga decides to return the Erasmus to Anjin-san. Mariko tells Father Alvito of a plot to murder a Christian lord on the Council of Regents.