Southwest border, rainy night.
A mudslide had just swallowed up a border village. The rescue team found the only survivor in the rubble - a seven-year-old boy, huddled under his mother's body, clutching a bloody military badge in his hand.
That's the logo of the border armed police force.
Twelve years later, at four o'clock in the morning, the training ground of Yanjing Special Warfare Academy.
A young trainee is doing an armed cross-country with a weight of 30 kilograms. This is the thirtieth lap of his extra practice today. No one ordered him to do this. After training every day, he would automatically practice more until he was exhausted.
His name is Lin Rui, a nineteen-year-old student majoring in reconnaissance and special operations at the Special Warfare Academy.
No one knew that he came from the village that was swallowed up by the mudslide, and no one knew that the owner of the military badge in his hand - the armed police soldier who desperately protected him before the mudslide came, was a stranger to him.
Lin Rui only knew that the soldier exchanged his life for his.
And all he can repay is to forge himself into a knife sharp enough to protect those who need to be protected just like he did back then.
