Cheng Mo originally studied Chinese medicine as a filial piety for his mother, but his mother was murdered and ended up as a suicide, so he switched to forensic medicine. He always believed that one day he could rely on his own ability to solve the truth of his mother's murder. In the process, I met Lin Sen, who was cheerful and optimistic but seemed to have an unspeakable secret. He was originally a criminal police officer but now works as a security guard for a company due to an injury. Determined to find out the truth behind his mother's murder, Cheng Mo accidentally discovered his true life experience and the truth behind Lin Sen's injury. Can Lin Sen really redeem Cheng Mo who is trapped in hatred?