International drug dealer TSUI KEI-HAP is taken into custody by INTERPOL agents then back to his country to face trial, but he has to be accompanied by his personal doctor HON YU the whole journey because he suffers an acute disease. Out of the blue, they are ambushed and attacked by killers when on board the plane, and KEI-HAP is injured and sent to a Hong Kong hospital. During his hospitalization, the Hong Kong police force, under the request of INTERPOL, dispatch the SDU led by CHIN HON-TO to protect and escort the two to leave Hong Kong safely...... CHUNG WAI-YAN would like to resume her former duty as a CIB officer, so she is required to undergo several psychological evaluations. Although her superiors such as ZI-LUNG and the others are very satisfied with her performance, she is still under probation……