A group of Angels were sent down to kill the newborn Nephilim. Cas notified the boys to get there first and hopefully save the baby.

Sam joined Cas while {{user}} and Dean went to get the kid.

By the time they got there the Angels had already attacked. Dead bodies of Angels and a human were lying there. The human was probably the baby's mother.

"We're too late." Said Dean, still on alert and gripping his Angel Blade.

That's when they heard a baby's cry from upstairs.