This starts directly after the first chapter of Harry Potter and the Philosophers Stone.
Dumbledore turned on his heel and was just about to apparite away when he heard the wing beats of an owl, and turned to see one fly up next to him and perch on the top of the fence. He stroked its head thoughtfully before removing the letter attached to its leg.
His face grew grim. It appeared as if tonight was not all good news, after all. The letter was an urgent plead for help. He immediately apparited to Goffs Close in Crawley, England, which was the address of some former students of Hogwarts, John and Mary Winchester and their two young sons. It seemed as if at the same time tragedy struck Grimald Place, It had struck Goffs Close. The street was swarming with muggle fire fighters and police trucks. Smoke covered the sky, and the house of the Winchesters house was destroyed. The roof three quarters of the roof had caved in and flames still licked through the windows despite the obvious effort of six fire trucks.
After scanning the area, he found the people he was looking for. On the curb across the street sat John Winchester, his elbows on his knees and his face in his hands, sobbing. Next to him stood his four year old son Dean who had tears streaming down his face as he tried to calm down his younger brother, Sam, whom he held in his arms. Mary was no ware to be seen.
Dumbledore walked over to them. Dean spotted him before John, and pulled on his dad's jacket until he looked up. The sight of a strange man with a long beard who wore a cloak confused him, for his parents didn't wear the traditional wizards wear. "I think it's a wizard." Dean whispered to his dad, who finally looked up.
John sat up quickly. "May I have a word with you?" Dumbledore said to John. He nodded and they walked down to the end of the street, out of hearing distance. "What has happened here?" Dumbledore questioned. John explained to him the events of that night.
He had gotten home from work late and had decided to watch some muggle television, which he had recently taken a liking too. He had fallen asleep on the sofa. It was about 1:30am when he had been woken up by Mary's screams in the middle of the night, coming from Sam's nursery. He had rushed up the stairs to find out what had happen and had seen Mary, a fire on the celling with a huge gash on her stomach. He grabbed Sam and passed him off to Dean and told him to take his brother outside. He then had reached for his wand and casted numerous incantations, but none of them seemed to have worked. The fire had gotten worse, and soon he had to run outside to avoid being burned to death himself.
"I left her." He sobbed. "I left her and now she's dead!" He began to cry again and collapsed on his knees. Dumbledore placed a hand on his shoulder, and thought over John's story. It was very troubling. What he had been describing seemed even darker then black magic. And for it to happen on the same night as the fall of Voldemort…
Another one of Sam's wails broke his train of thought. He helped John to his feet. "I will make sure the ministry makes a full investigation. This was dark magic at work, darker then I have ever seen. For now you and your sons should go directly to the ministry. And John… I am truly sorry." He nodded, but Dumbledore could tell by looking into his eyes that he was a broken man. John walked over to his sons and lifted one into each arm and disapparited.