heng Yuanhai joins the naval army with great expectations of making contributions to a strong Chinese naval force. Lu Huai, chief of the navy base, appoints Zheng Yuanhai to a deserted place in order to test his resolution. However, at the beginning of his training, Zheng Yuanhai always conflicts with Chen Jianjun, director of Missile and Naval Mine Division. Ten years later, Chen Jianjun becomes a destroyer captain, and Zheng Yuanhai a frigate captain. In the fight against an unknown invasive submarine, Zheng Yuanhai's wisdom and Chen Jianjun's courage come together in building a strong sea defense. However, at the critical moment of campaigning for flagship captain, Chen Jianjun's momentary slip results in the escape of the unknown submarine. When he takes off his army uniform, Chen Jianjun chooses Zheng Yuanhai to realize the great expectations of his generation for him. Zheng Yuanhai, who starts from a university student recruited in navy, becomes a flagship captain after going through all the hardships and setbacks, and eventually leads a fleet towards the blue sea to write a beautiful story about loyalty and strength.