Xiao Zihan, a female medic from the special forces, was invited by her best friend to come to S city. She thought it was a simple vacation, but she was unexpectedly involved in the incident. Here she met the love of her life - Pei Junyuan, a mysterious man walking on the edge of black and white.
At the invitation of his brother, he stayed to help solve the case. What he thought was a simple drug trafficking case turned out to involve national security. As everyone worked together to solve the incident, the relationship between the two also heated up.