Blackthorne and Mariko test their new alliance as they train Toranaga's gun regiment for war. Yabushige must navigate his past promises to Ishido when an old friend comes to the village.

Blackthorne and Mariko struggle to contain the secret that could get them both killed. Yabushige searches for the spy who has betrayed his intentions to Lord Toranaga.

Mariko arrives in Osaka for the fight of her life. Blackthorne and Yabushige scramble to save their own heads as their options dwindle.

In the wake of a tragic death, Blackthorne finally considers the true nature of Toranaga's plan.