I was a witness, so I can tell how it was, even though for eight years Marta insisted that nothing happened that night. She is my cousin, two years younger than me. That winter she was twenty-two and in love with Domagoj, a ski instructor from Guča Gora, who had a snowboard, a rented room at Babanovac, and debts. Her father ran two pharmacies in Travnik, and her mother had already chosen the dentist's son from Vitez for her. People called Domagoj a seasonal worker, which in our family was worse than a curse word.

In February Domagoj was leaving for a season in Austria. Before that they wanted to bind themselves somehow, so that no one could arrange anything for Marta while he was away. No priest would marry them without papers, and papers meant parents. So they came up with a vow: at night, in the wooden chapel above Babanovac, with candles and two witnesses, me and my Ivica, in words they had written themselves. "This is not a wedding," Marta told me. "This is a promise. The wedding will be in April, at the municipal office." I told her that a promise in a chapel weighs more than any paper. "That is the point," she said.

It was a Saturday in the middle of January, and since noon the forecast had been warning of a blizzard. We drove up from Travnik in my old Passat. Marta was in a white jacket, with her grandmother's white scarf over her hair, because she wanted to have at least something white. Domagoj was supposed to come from the other side, from the hut below Devečani, on the ski school's snowmobile, because the road on his side was closed.

By the time we reached the chapel, the snow was falling sideways. The power had gone out at Babanovac, so even the little lamp above the door was dead. We lit the candles we had brought. Marta knelt in front of the altar, and every ten minutes Ivica went out with a flashlight and came back whiter. Domagoj's phone was unreachable. Ten o'clock. Half past ten. Eleven.

What was happening to Domagoj we learned only later. He set off from the hut at nine, and within five minutes the blizzard had buried the track. He drove in circles across the plateau, the snowmobile's light showing him nothing but snow, and in the end he ran into the fence of some shepherd's hut, miles from the chapel. He went inside, with no signal, and until dawn he fed the stove with someone else's wood.

At a quarter past eleven the chapel door banged open. A man came in covered in snow, with a hood up and a scarf over his face to the eyes. Ivica let out his breath. "Where have you been, man! Come on, quick, the candles are burning down." I pushed him toward Marta. He looked at us, at the candles, at Marta on her knees in the white scarf, and said nothing. I should have seen that he was taller. Only later did I remember that Domagoj's jacket was orange, and this one was black. In the dark everything is the same color.

I read from the paper the words the two of them had written: that before God and these witnesses they promised each other faithfulness, and that they would look after each other as long as they lived. The man repeated them quietly and hoarsely, and I thought it was from the cold. Marta said hers loudly, as if she wanted them heard all the way down in Travnik. Then Ivica, laughing, said: "Now the kiss." The man lowered his scarf. Marta lifted her face and screamed.

It was not Domagoj. It was a young man none of us had ever seen, unshaven, red from the wind, with the smile of a man who has won a bet. "Excuse me, miss," he said. "I thought it did not matter to you who it was." He was out the door before Ivica could reach him. From below came the sound of a snowplow, then an engine, and through the snow we saw two red lights following the plow down the mountain. Marta collapsed onto the cold boards. Her grandmother's scarf ended up in the wax.

In the morning rescuers found Domagoj, alive, with frostbitten fingers and no fault at all except that he did not know the mountain in the dark. Marta lay in a fever for two weeks, and her parents never learned what had happened; they thought it was pneumonia. When she got up, she told Domagoj she could not. She had spoken a vow, and it was spoken. He thought it was an excuse. He was ashamed, left for Austria in February, and stayed. Three years later I saw his wedding in Tyrol on Facebook.

Marta finished her pharmacy degree and took her place behind the counter in her father's pharmacy in the old town. She turned down the dentist's son, then an engineer, then a judge from Zenica. In town people said she was proud. Her mother cried, her father stopped asking. Her grandmother's scarf, with its wax stain, lay folded in the drawer under the register, and only I knew it.

In the seventh autumn an engineer came from Zagreb to supervise the building of the bypass and rented the apartment above the pharmacy. His name was Tihomir. Every week he came down for something, allergy pills, bandages, eye drops, and he said little, but he looked at you the way people look when they are listening for something. In the evenings he walked along the Lašva. Marta began walking at the same hour. "He doesn't ask me anything," she told me, "and I tell him everything."

But Tihomir asked for nothing more than a walk, not in November, not in February, even though Marta saw, and I saw too, how his face changed when she walked in. In March, on the ramparts of the old fortress, he told her he had to tell her something so that she would not think he did not love her. Eight years earlier, in January, he had been coming back from skiing and got stuck in a blizzard on Vlašić. He saw candles in some chapel. Inside they had taken him for a bridegroom, and he, out of stupidity and because he was twenty-six and thought the whole world was a joke, had spoken a vow with a girl whose name he still did not know. "I said before witnesses that I would look after her," he said, "and I left her on the floor. Since that night I cannot promise anyone anything."

Marta was silent for a long time. Then she asked him what he had said on his way out. Blushing, he repeated the same words about how it probably did not matter to the girl. "It did matter to her," said Marta. "Look at me more closely. Remember the candles." Tihomir went pale and sat down on the wet stone of the rampart, as if his legs had given way.

She told me all of it that same night, in my kitchen, laughing and crying at the same time. She took her grandmother's scarf out of her bag, the one with the wax stain, and spread it on the table. I asked her what she would do now. "Get married," she said. "But this time, the papers first."