Imperial Guard Meets Runaway Prince

Qian Yuxi is an imperial guard newly appointed by the king of the legendary Shang-Yi, a mystical island city located off the ends of the world, as people often said. However, she carries a secret, and that is how she had turned into a completely different person after a near-death experience when she was ten.
Zhan Peng is a runaway prince from a faraway state. To escape the harsh rules of the palace and to help his sworn brother Yang Tian uncover his true identity, they make the risky journey to Shang-Yi where they pose as civilians and eventually find work there when Zhan Peng's savings run out.
However, what happens when Qian Yuxi hires Zhan Peng and Yang Tian as mercenaries for her secret mission? And why does Zhan Peng seem to know her from before, yet she doesn't recognise him?
When an arrogant and feisty guard meets the calm and composed dignified prince, what will come out of their collaboration?