Blaise's mother always taught him that self-preservation was the only rule in life, but he finds that it's easier said than done when he ends up having to use all his deception and intelligence to live through being thrown into Slytherin house in 1944. When joining a young Voldemort is just as dangerous as opposing him, Blaise doesn't have many appealing options to choose from.
By a strange turn of events and a bout of mistaken identity, Voldemort accidentally attempts murder on the wrong baby resulting in a world where Luna Lovegood is the Girl-Who-Lived and Dumbledore is convinced she is the one in Trelawney's prophecy.