Great! Here's **Chapter 5: Letter in the Mailbox** in its full, expansive novel form: ---

 

## **Chapter 5: Letter in the Mailbox**

The morning in the city was quiet, but Commissioner Jakub Nowak sensed something was wrong even before he left the house. The feeling of unease was subtle—a slight tingle in the back of his neck and a tension in his shoulders, which Argo immediately sensed. The dog raised his head and approached the mailbox at the entrance.

Jakub approached and reached into the mailbox. Among the daily mail, he found a small, unsentenced gray envelope. The message was short but unsettling:

**"A shadow is coming over the city. Be alert, Commissioner."**

The dog growled softly, looking at Jakub expectantly.

"I see you feel the same way, Argo," the commissioner murmured. "Someone's trying to test us."

---

### **First Clues**

Jakub wasted no time. He set off toward the police station, and Argo sniffed the air, leading him along side streets and alleyways. The scent was subtle, almost invisible to an ordinary person, but the dog detected every nuance: the scent of paper, the traces of a burnt candle, tiny crumbs on the cobblestones.

"Argo, we're going carefully. This isn't an ordinary letter," Jakub said, looking at the dog. "Someone wants to involve us in a game."

The dog quickened his pace and stopped in front of an abandoned warehouse next to the police station.

"There's something here... I can feel it," Jakub whispered, slowly entering.

--

### **The Clue Leads to a Psychological Game**

The warehouse held further clues: small objects arranged in irregular patterns, encrypted notes, and strange symbols on the walls. Everything seemed to be part of a carefully planned psychological game.

"Someone wants us to follow them… and make us feel watched," Jakub said, analyzing the arrangement of clues.

Argo sniffed carefully, stopping at a box on the ground. Inside were more sheets of paper, on which someone had written instructions: "The truth is closer than you think. Check the old places where shadows live."

"Well, Argo… it looks like a new game has started," the commissioner said, petting the dog's head. "And I think someone is testing us."

--

### **Discovering the True Motive**

Over the next hours, Jakub and Argo tracked down clues, analyzed symbolism, and connected the dots. It turned out the perpetrator was trying to expose minor frauds and irregularities around the precinct, testing their reflexes, observation skills, and ability to cooperate.

"Argo, you see?" Jakub said, looking at the dog. "This isn't a dangerous case… at least not physically. But it's testing our intelligence and patience."

The dog barked softly, as if confirming the commissioner's words.

--

### **Solving the Puzzle and Reflection**

Jakub and Argo discovered that the "Shadow in the City" was a young computer scientist who wanted to test the local police's ability to respond to subtle signals of danger. The puzzle was dangerous only psychologically—it required cunning, patience, and intuition.

"Job well done, Argo," Jakub said, petting the dog's head. "Sometimes a puzzle doesn't require pursuit or violence, just patient investigation and a keen nose."

The dog sat down at his leg, looking into the commissioner's eyes. Jakub smiled slightly, knowing that he and Argo were ready for whatever the future held—both dramatic puzzles and more sedate ones that required cunning and intelligence.

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This chapter expands on the mini-adventure with the letter, adds suspense and a psychological dimension to the puzzle, and showcases the unique partnership between Jakub and Argo.