Shock, Final Mission

At four o'clock in the morning, when the sky was just beginning to brighten, Old Man Li set off on his tricycle. Before dawn, he wanted to clean up all the areas he was responsible for.

Very soon, Old Man Li arrived at his area of responsibility.

When he was cleaning the road, a stray dog suddenly jumped out from the street.

"Hey, why are you running around?" Old Man Li was shocked.

But in the next moment, he found the faint red paw print left by the dog on the ground.

"Well, what did he step on?" Old Man Li looked at the paw print and looked at the alley. He saw two people standing in the alley, wearing big red clothes. They stood there motionlessly.

Old Man Li looked puzzled. It was not yet dawn. Why were there two people standing in the alley?

He slowly walked over. The closer he got to the alley, the brighter the dog paw print on the ground became.