Field doctor Han Jin was scolded as a coward for refusing to kill wounded enemy soldiers and was expelled from the military. When the enemy's special forces raided the frontline medical station, he picked up a scalpel and cut open the enemy's heart. He died on the spot and the entire network exploded. Iron-Blooded Battalion Commander Lin Xiao investigates the truth, but is shocked to realize that every blow of this 'coward' is tearing apart a biological weapons conspiracy that has been covered up for seven years. The enemy's surgical captain Chen Yan is hunting for the serum. Inspector Su Ling's file is counting down, and the orphan Xiaodao is using his little hands to polish his first scalpel.
