I heard this story from the brother of the person it happened to:
The father of a prominent family in Bnei Brak is a talmid chacham, and the sons are avreichim who are ovdei Hashem with genuine yiras Shamayim. Unfortunately, their oldest son fell victim to the lures of the streets and went very far off the derech, Hashem yishmor.
Several years ago the rebbetzin, the mother of the family, passed away. Her petirah touched the heart of her eldest son, and he committed to keep Shabbos, l’ilui nishmasah. He still hasn’t done complete teshuvah, and he continues to spend time with friends who are off the derech, but, come what may, he keeps Shabbos.
Before Simchas Torah, his friends told him they were going to some sort of festival down South, and they invited him to join them. This festival was not in the spirit of Torah and not anything his parents would approve of; it was “in the spirit of nonsense” and spiritual harm. It was certainly not appropriate for a bachur from such a chashuveh family to be there at all, but he agreed to the invitation, with one caveat: “I’ll come, but I’m keeping Shabbos.”
How would he keep Shabbos with all the emptiness going on all around him? He went there with a trailer, and he prepared a blech with cooked food. He organized the trailer nicely and set up electricity so he wouldn’t have to turn on the lights on Shabbos, chas v’shalom. He truly did everything like a kosher Jew; he created an island of Shabbos in the midst of the desecration.
Since he had already brought along all the equipment and had prepared so much, he invited some friends into his “Shabbos room” and traveled down South. He had just parked the trailer near where the terrible party was to be held that night, and he got a call. His father was on the line.
“Listen to me,” he told his wayward son. “I want you back here in the house. Now.”
“Why, Abba? What happened?”
His father himself has no idea what happened. He felt he was being pushed from on High, and he has no way to explain the strength he was suddenly expressing. “You need to be home for Yom Tov. There’s nothing to talk about.”
“But I’m already here, and I promise I’ll keep Shabbos. I have a whole trailer here with everything we need.”
“I don’t care about that,” his father answered. “I haven’t gotten involved in your life before. This is the first thing I’m asking of you. Come.”
“But will I make it in time? It’s a long trip.”
“You’ll make it. Leave right now. I’m waiting for you.”
This precious bachur listened to his father shlit”a, and to his mother in Gan Eden. He traveled home immediately, leaving behind the trailer and his friends.
His life was saved. Now we understand that Hakadosh Baruch Hu put this extra stubbornness into the heart of his father in order to save the life of his son.
But the story doesn’t end there.
When the lowly murderers infiltrated, the bachur’s friends hurried into the trailer. They locked the door and lay down on the floor, with terrible fear of what was to come. The terrorists advanced in the direction of the trailer – a flimsy structure made of simple walls and a simple door that could be easily broken. The terrorists tried to break the door down but did not succeed. With great cruelty, they lit a fire underneath the trailer and only then left the premises.
The fire didn’t reach the trailer; it went out on its own. The lives of those friends who were inside the “Shabbos room” were saved.
Shabbos saved them.