Sakib Delić stood before a glass display case in the Kapetan shop on King Tvrtko Boulevard, choosing the camera with which he would destroy two lives. Less than an hour earlier, when a fault in a transformer had sent the whole shift home from the steelworks, he had unlocked his apartment on the sixth floor and found in the living room his wife Mubina and Mehmed, the neighbor from the fifth floor. The curtains were drawn. Mehmed was wearing his slippers. Mubina was the first to jump off the couch, Mehmed the second, and the slippers stayed on the rug as evidence. Sakib said nothing. He turned around, closed the door and walked down all six floors, because he could not wait for the elevator.

Kapetan was half a fishing shop and half something else. On the left side were rods, lures, rubber waders up to the waist and boxes of hooks sorted by size. On the right side, behind glass, was what Sakib had come in for: tiny cameras shaped like chargers, alarm clocks and key rings, devices for tracking cars, and voice recorders as thin as a stick of chewing gum. Above the case it said Security. Behind the case stood a salesman of about sixty, with a mustache and glasses pushed up onto his forehead, smiling like a man who had spent the whole morning waiting for him in particular.

"I need a camera," said Sakib. "A small one. So it can't be seen." "For a business or for a home?" "For a home." The salesman nodded like a doctor whose patient has just shown him where it hurts. He introduced himself as Rifet and took out of the case something that looked like an ordinary phone charger. "This is the best we have. A picture as sharp as at the movies, it records in the dark too, it switches on by itself as soon as anything moves. You plug it into the socket and forget about it. It doesn't forget."

Sakib took the charger in his hand and at once saw everything. The camera in the socket behind the television, pointed at the couch. Tomorrow he goes to work as if nothing had happened. The day after, he has the footage. And then his mother-in-law celebrates her sixtieth birthday at the restaurant by Kamberovića Polje, all the relatives from Kakanj and Vareš at a long table, and he stands up with his glass, connects his phone to the big screen and says: this is my present. He saw Mubina's face. He saw Mehmed's wife Hasna knock over a glass of juice. He saw his mother-in-law sit down, for the first time in her life without a word. It was so beautiful that he closed his eyes.

"There's an app too," Rifet went on. "You watch live, from work, from a café, from Germany if you like. The recordings go onto the internet, so even if someone finds the charger, the footage stays. One of my customers watched his house from a fishing trip on the Drina. He caught two grayling and one burglar on the same day." He laughed at his own story, briefly, as if he had told it a hundred times already.

Sakib opened his eyes. Someone at that dinner, he thought, would still ask where the footage came from. And that someone would surely be his brother-in-law Nail, who worked for a lawyer in Sarajevo and always asked exactly the wrong question. In front of everyone Nail would say that people must not be filmed without their consent, that there was a penalty for it, and that the one sitting in court would not be Mehmed but him. Mehmed would be the neighbor who had dropped by for coffee. He would be the man who had hidden a camera in a charger. He put the charger down on the glass, carefully, as if it were hot.

Rifet did not notice, or pretended not to. He took out a gadget the size of a matchbox. "Or this. A tracker. You stick it under the car, the magnet holds even on cobblestones. On your phone you see where the car has been, how long it stood there and at what address. Women buy these most, you know. Husbands buy cameras, wives buy these. A man wants to see, and a woman wants to know where." Sakib imagined Mubina's car with that little box under the bumper and an app telling him the same address every day, their own, because Mehmed lived one floor down. Day after day the device would assure him that his wife was at home. That made him feel worse than the camera had.

Then he could do it differently, he went on thinking. Without any gadget at all. Write everything in the group Zenica Without Filters, which had forty thousand members and where someone argued about parking every day. First name, last name, floor. Let the whole city know who wore other men's slippers. In his head he was already writing the first sentence and deleting it, then writing a second. And then he saw the comments. He saw women who had never met him writing under his post: and where was he, he must work night shifts, that kind always does, no wonder. He saw hundreds of laughing faces. He saw that in the locker room at the steelworks he would be the one with the slippers until he retired.

Meanwhile Rifet was talking about batteries that last seven days. The simplest thing, Sakib thought, would be to go down one floor and ring Hasna's bell. No footage, no group, nothing at all, just say: your husband is sitting in my slippers. He imagined Hasna opening the door in her apron, a wooden spoon in her hand, listening, her face tightening. And then he imagined the next twenty years. The elevator in which the four of them would ride together, staring at the numbers above the door. The meetings of the building council. The shared storage room in the basement. Hasna would forgive Mehmed, because she forgave him everything, from loans to the betting shop, and Sakib would forever remain the man who had rung the bell.

"Let me tell you something," said Rifet, and lowered his voice, though there was no one else in the shop. "I bought all of this for myself first. Eight years ago. I thought my wife had someone. I put up three cameras, two in the apartment, one in the car. And I was right." Sakib looked at him properly for the first time. "And what did you do?" "Nothing. I watched. For a year I watched, every evening, like a TV series. Then she went off to Slovenia with him, and I was left with the cameras. My brother-in-law gave me this job so I would have somewhere to go in the mornings." He pointed his glasses toward the case. "They say I'm the best salesman in Zenica. I know what a man needs before he knows it himself."

Sakib stood there looking at the charger on the glass. He saw himself sitting every evening on the couch at his mother's in Kakanj, because the apartment was Mubina's, from her father, and watching his former living room on his phone: Mubina wiping the table, Mehmed coming over with burek, the television on, and he watching, like a series, for a year, while his mother told him from the kitchen that she had said so back at the wedding. He saw the court too, and the lawyers, and Nail shaking his head. Every plan he had made between the sixth floor and the Boulevard was turning out, one after another, to be a door that led into an even smaller room.

"So, are you a fisherman?" Rifet asked suddenly. "You have the hands for a rod. You can tell by a man." Sakib said he was not. As a boy he had gone with his father to the Bosna below Raspotočje, but that was long ago and his father had always held the rod. "Ah, you never forget that," said Rifet, and he was already coming out from behind the case to the left side of the shop, among the rods. "The Bosna is cleaner now than it has been in thirty years. Chub, barbel, there's even trout up toward Vranduk. And for a man with a problem at home, the best thing is to sit by the water. Water doesn't ask questions."

He took down from the wall a net on a long aluminum handle, folding, green, with a rubber mesh. "A landing net. The handle extends to six and a half feet, and the mesh is rubber, it doesn't hurt the fish and the hook doesn't get tangled. This is the first thing a fisherman needs, before the rod, before anything. Without a landing net you can catch a fish, but you can't get it out of the water." Sakib looked at the net and did not know what to say. He was ashamed to walk out of the shop empty-handed after everything this man had told him, as if he too were one of those who only watched.

"How much?" he asked. "Forty-five marks. Forty for you." He paid by card. Rifet tried to wrap the net in newspaper, though it would not be wrapped, so the handle stuck out at both ends, and he gave him a free calendar with the fish of Bosnia and Herzegovina to go with it. At the door he held out his hand. "And for the camera, when you make up your mind, you know where I am. Most of them come back." Sakib said he would come back, and he heard how much it sounded like a promise.

Outside it was a sunny October day. Above the steelworks the smoke shone white as if it were a holiday, and on the Boulevard high school kids were eating pizza out of boxes and laughing at something on a phone. Sakib stopped in front of Kapetan's window and in the glass saw a man in a work jacket, with a fishing net over his shoulder and a calendar under his arm, standing in the middle of Zenica with no idea where to go. He recognized him only when the man straightened his collar.

He did not go home. He set off toward Kamberovića Polje, where there is always someone with a rod on the bank of the Bosna, so that he could at least see how it was done.