Why is Tang Ying, the soul of the ocean, a spy?

The plot setting. In the TV series Soul of the Sea, the plot sets Tang Ying as a spy. The Soul of the Sea was jointly created by the Television Art Center of the Political Department of the Navy and Shanghai Dingli Film Co., Ltd., directed by Fu Mingbao, written by Zhang Shoujun and Zi Han, and starring Apollo, Zhu Jie and Jungle.