Along the way, the wind was gentle, and Su Shi walked slowly to the front of the study.

The door to the study was empty, and from time to time there was a sound of conversation coming from inside, but the sound of conversation was so low that even if I tried to listen, I couldn't hear it really.

Su Shi stood outside the door for a while, then calmed down, pushed open the hidden door and walked in.

Zhou Jin, Qin Nan and Chen Xiaolan were chatting casually, and when they saw Su Shi pushing the door in, they stopped talking, and they all looked at him with strange expressions.

Their eyes made Su Shi strange, he stopped and couldn't help asking, "Why are you looking at me like this?" ”

Zhou Jin and Chen Xiaolan's faces were slightly red, especially Zhou Jin, she was already a little weak-hearted, and she no longer dared to make contact with Su Shi, so she had to look at Qin Nan.

Although Qin Nan was also shy, her relationship with Su Shi was different from others, so she didn't avoid Su Shi's inquiring gaze, and said softly: "Just now we heard from Brother Lin that you came back late yesterday, so you didn't have a good rest. ”

"Don't listen to his nonsense." Su Shi said casually: "It's not yet late when I come back, how can I say it's late." ”

"But you left the vault before the end of yesterday."

Zhou Jin and Chen Xiaolan looked at Su Shi again, because they also wanted to know where he had gone in the past two hours.

Su Shi also understood what they meant at this time, but he didn't answer them immediately, but sat down silently, pondered for a while, and then looked up at Zhou Jin.

"Was there anything special going on in the palace yesterday?"

"I haven't heard of anything special going on." Zhou Jin thought about it carefully, shook his head slightly, and then stared at him again: "Why did you suddenly ask this question?" ”

"Really?" Su Shi was a little strange: "After the purple smoke rises, everything in the palace is really as usual?" ”

"Maybe the other side is still plotting." Zhou Jin muttered: "I have already told my father about this, and my father has also strengthened the vigilance in the palace, and it is not so easy for the other party to create trouble in the palace." ”

There was a trace of worry in Su Shi's eyes, and he couldn't help but sigh: "But I can feel that their plan has begun to be implemented." ”

Zhou Jin's face changed slightly: "Has it already been implemented?" Why do you feel this way? ”

Su Shi smiled bitterly: "I just feel this way, but what I hate is that my feelings are rarely wrong." ”

Qin Nan suddenly said on the side: "Actually, as long as you find the person who is hiding in the palace, everything will be solved." ”

Zhou Jin shook his head and sighed: "My sister doesn't know, in the palace where you can see the fireworks of Guangdu Temple, there are thousands of eunuchs, palace maids, guards and miscellaneous servants, and it is impossible to investigate. Even if there are a few people who are more suspicious, the secret guards have no results in checking back and forth. It is undoubtedly a needle in a haystack to find out the people hidden in the palace through limited clues. ”

Qin Nan looked at Su Shi hesitantly, but Su Shi didn't have any expression, Qin Nan wanted to speak and stopped, and finally kept silent.

However, Zhou Jin saw that Qin Nan's expression was different, and he seemed to know something, but he seemed to have some scruples.

It was a matter of his father's safety, Zhou Jin naturally would not give up, and immediately asked, "Does my sister know something?" ”

Qin Nan didn't answer her, but couldn't help but glance at Su Shi again.

Now even if Zhou Jin is blind, he can see that the person Qin Nan scruples about is Su Shi, although Zhou Jin doesn't know why, he can't help but look at Su Shi with doubts.

Su Shi naturally couldn't sit on the Diaoyutai anymore, smiled reluctantly at Qin Nan, and said, "If you think of anything, just tell Her Royal Highness the princess directly." ”

Qin Nan still seemed a little hesitant: "Will it ruin your plan?" ”

Su Shi propped his head with one hand, and his expression looked a little helpless: "My mind is already in a mess now, what plan do I have." ”

Qin Nan was puzzled: "In that case, why didn't you tell Her Royal Highness the Princess?" ”

Zhou Jin was listening to a book from the side, and then couldn't help asking, "Tell me what?" ”

"Who is the spy hidden in the palace, Su Gongzi should have known it a long time ago."

Qin Nan's words were like a thunderbolt from the sky, not only Zhou Jin was shocked, but even Chen Xiaolan looked at Su Shi incredulously.

"Really!" After Zhou Jin was shocked, he still looked at Su Shi in disbelief, and then felt a feeling in his heart, and looked at Qin Nan again: "My sister also knows?" ”

Qin Nan said slowly: "I also returned to the mansion last night, and I came to my senses when I remembered Su Gongzi's words. ”

"What?"

"Regarding that purple smoke, yesterday Su Gongzi asked Her Royal Highness the princess a question, how many times has the purple smoke been fired?"

Zhou Jin nodded involuntarily: "He did ask this question." ”

Qin Nan looked at Su Shi: "Presumably you had the answer in your heart at that time." ”

Su Shi had no choice but to explain: "That's just my guess, so I didn't say it." ”

Qin Nan smiled: "After returning to the mansion, I think about it carefully, but I think your guess is correct. ”

Seeing that Qin Nan and Su Shi were still playing dumb riddles with each other, Zhou Jin felt a little sour in his heart for no reason, but he couldn't care about these at this time, and hurriedly asked, "Do you really know who the spy hidden in the palace is?" ”

Qin Nan saw that Su Shi did not object, so he said slowly: "Although it is ingenious to use heterochromatic smoke to communicate, there are also drawbacks in it, that is, how to let the spies in the palace see it. ”

Zhou Jin was puzzled: "The smoke rises into the air, as long as you look up, you can see it, how can this become a disadvantage?" ”

"Her Royal Highness the Princess once said that the purple smoke did not exist in the air for long, how could the person who set off the purple smoke guarantee that the spy would definitely see the purple smoke at that moment?"

"The people in the palace have their own affairs, it is impossible to stare at the Guangdu Temple all day long, to see if there is any strange smoke rising, if the strange smoke rises, the spy has already gone out of the palace to do business, or in the hall to listen to errands, or rest in the house, how can he see the strange smoke?"

Zhou Jin groaned: "When the smoke rises, someone will always see it, and then spread it to each other, and it will naturally reach the ears of the spies, so he doesn't need to see it with his own eyes to know about the smoke burning in the breadth." ”

Qin Nan shook his head lightly: "First, the perennial incense of Guangdu Temple is surrounded by incense, most people are accustomed to it, even if there is a strange smoke rising, it is just a novelty, and it may not spread around." Moreover, the information transmitted by the smoke must be very urgent, and it is impossible to rely on human words to determine that the information is unreliable, and if they hear it wrong, are they not afraid of making a mistake? ”

In the end, Qin Nan concluded: "So if you want to use foreign smoke to transmit news, one way is to set off different smoke through multiple time periods and multiple times to ensure that the spies in the palace will definitely be able to see it." But the purple smoke was only set off once, which shows that the other party did not use this method, so only one last method remained. ”

"By what means?"

"No matter when the smoke rises, the spies lurking in the palace will inevitably be discovered, and only one of them can do this."