In a prelude to "House of M", Magneto's daughter Scarlet Witch suffers a mental breakdown and causes the death of several Avengers. Magneto brings her to Xavier and asks him to use his mental powers to help her. Although aided by Doctor Strange and the appearance of Cassandra Nova, Xavier is unsuccessful. Xavier orders a meeting of the X-Men and Avengers to decide Wanda's fate. Her brother Quicksilver, believing the heroes plan to kill her, speeds off to Genosha and convinces Wanda that she could right the wrongs she inflicted by using her powers to alter reality.