In the office of the Security Department of Times Square, a man in a dark blue felt hat is explaining something to two men.

When the man left, he closed the door by the way, the office was very simple, there was an old computer on the desk, the system was still the popular Windowsxp a few years ago, there was a potted plant next to the table, it was very high to the ceiling, in addition to these, it was a filing cabinet and a floor-to-ceiling hanger, back to the monitor, the whole display was very clean, except for the necessary shortcut program was an H.263 format video file, Cai Le skillfully controlled the mouse, and glanced back at Zhang Mao on his side, nodded, the video began to play, both of them moved forward to the display, and the video was playing, Cai Le has been staring at the video screen, and Zhang Mao, who was looking down on the side, actually yawned after a big job, and even Cai Le responded as if he was infected, this yawn was halfway through, and he instantly grabbed all of Cai Le's sight, a black shadow appeared in the dim video screen, Cai Le pressed the space bar, Zhang Mao glanced at Cai Le and did not ask any questions, raised his hand, and walked near the window, Cai Le turned his head, the picture of the display screen gradually became clear, the figure was a little outlined, and when the footsteps in the room stopped, Cai Le pressed the spacebar again, and the figure began to move, first looking around, and then roughly with a clear purpose, The clip of walking into the Christmas tree has long been guessed, the man opened the door of the Christmas tree, poked his head in, from the perspective of the surveillance video, the situation inside was completely blocked, and finally the man was ready to take out the souvenirs in the tree, but was interrupted by the figure that appeared at the other end, Cai Le turned around, Zhang Mao's expression seemed to say, this is the case, Cai Le did not see the curious staff in the video to lose the key, but guessing from the content of the video, the staff was interrupted to do what the administrator did to the administrator came to him and scolded him, to the next administrator bent over to look at the Christmas tree, and finally the administrator got up and scolded him, Everything is fine, then those two people may not be lying, this should be a fact, Zhang Mao didn't say anything, like a winner, looking at Cai Le, who was repeatedly pressing the backward and forward buttons, the video returned to the last part of the figure where the two people left, the video continued to play, the time displayed in the upper right corner of the video was advanced for about ten minutes, and finally the appearance of a figure made Cai Le and Zhang Mao see the dawn, the person in the video sneakily entered the Christmas tree, Cai Le pressed the space bar, and the picture was frozen to half of the person's body and the tree were integrated, Cai Le pressed the space bar again, the man and the tree were completely reduced to one, and Cai Le fell on the back of the leather chair, didn't speak for a long time, Zhang Mao said proudly

"The truth is as I said, that is to say, it was actually an accident, so now we just need to find that souvenir to close the case, hey, no!" Zhang Mao paused, took out the flat cigarette case from his trouser pocket, and the hand that took out the cigarette case was halfway raised up and froze in mid-air

"So where did the jackpot go" Zhang Mao looked at Cai Le, waiting for him to answer, Cai Le continued to mobilize the video recording,

"Team Zhang, let's take a look, take a closer look!" is still the familiar clip just now, the figure that appeared later is slowly merging with the tree, after the playback, Zhang Mao did not give an opinion, Cai Le continued to answer

"Then let's take a look at the previous clip" Cai Le used the mouse to locate a progress percentage, which was the first mysterious figure, that is, the picture where the curious staff went to get the souvenir, and it can be seen in the picture that half of the man's body was always left outside the tree, and finally because of the arrival of the administrator, part of the tree left in the tree came out, and the entire tree door was closed

"It looks like two people enter differently"

"What else?"

"You're blinded by what you see"

"Blinded? I didn't see there?"

"Wait a minute, I'll show you something" Cai Le took out his mobile phone, and Zhang Mao's time for half a cigarette passed

"Alright!" Zhang Mao approached the place where the voice sounded

"Look!" Cai Le put the phone in the left corner of the display screen, as if it was a comparison, Zhang Mao squinted, carefully observed the picture presented by the two interfaces, and finally Zhang Mao exhaled

"So this is it, right, but what's the difference?"

"The way through the door!"

"How?"

"If you haven't already, you should remember how we all looked at that Christmas tree!"

"Pull away, and it's a breeze"

"Yes, just pull away"

"What is the difference between here and here, is it the way?" said Zhang Mao, pointing to the images presented on the two screens

"Yes, because of the angle of this video, coupled with the clarity of the whole video, we basically don't see how the door is opened, that is, we don't know if there is a way to open the door of the Christmas tree without pulling it"

"Push away!"

"That's right," Zhang Mao seemed to have his head into the interface

"I can't see how I got in, and what difference I made when I got in?"

"Yes, you turn around" Zhang Mao turned around with Cai Le's meaning

"In front of you is the door of this house"

"Well, then what"

"You go to him, open it" The footsteps became slightly lower, stopped, Zhang Mao twisted the door lock, the door was opened, Zhang Mao pushed the door back again, boom, Cai Le spoke

"That's it!"

"The person inside can't go the other way he can only open the door to get out, that's it, right!"

"However, the way we have seen to open the door is ......," Zhang Mao patted his head with his hand

"It's all open, and it's all from the outside"

"That's it, then I have a hypothesis, if we are inside, we can't push the door open, and we can't get out without the help of external forces. ”

"So it's possible that he was frozen to death in this way, right?"

"There are still a lot of questions, such as why he didn't call for help, why didn't he find a way to use external force, that door was actually very easy to open, it couldn't be that there was no external force that could be used at all!" Zhang Mao lowered his head, thinking about the question just now, and raised his head in amazement

"Let's talk about how you found out the secret of this door!"

"Well, good" Cai Le mobilized the video again,

"Probably this" Shun was in the two places that Cai Le pointed to, and Zhang Mao looked at it in detail

"What's that feeling, the video here highlights a little bit," Cai Le enlarged the video

"It's clearer"

"It's true that there is an extra dot on the tree here, so what is that dot?" Zhang Mao pointed to a piece of the computer display screen

"It's a keyhole, but fortunately the man was extremely scared at the time, if I were a little more daring, I don't think we would be able to see it here."

"If the door is a little bit back, this little dot will be turned away by the door, right?"

"Well, it's mainly a problem with the angle of this surveillance, and there is only one camera in this area that can see the surveillance footage of the trees."

"Plus it's dark, so we don't know exactly how that door opened, right?" Zhang Mao continued Cai Le's words

"Yes, that's it!" The man in the dark blue felt hat appeared in front of the two people again, the two people explained something to him, and saw that the man took out a USB flash drive and handed it to one of them, the two people left the office and walked straight in the direction of the Christmas tree, the periphery of the tree was surrounded by a yellow cordon, and there were several people standing around, probably the person who was entrusted to protect the tree, Cai Le and one of them explained something, the cat entered the cordon with his waist, Zhang Mao also followed, Cai Le stood at the bottom of the tree, the branches and leaves of the tree and the upper half of the body were gone, leaving only the lower torso, Cai Le opened the tree door, it was still so easy, Then he pushed the tree door back tightly, the door was blocked by something, pushed it up, but it was covered quite tightly, Cai Le's whole body entered the tree, the door was open, his eyes looked around the edge of the entire door, it was empty, Cai Le pulled his hair and secretly screamed that it was not good, this is not true at all, where is the entrance, how to achieve it?

Cai Le and Zhang Mao looked at each other, but neither spoke.