James, Lily, and Sirius are ambushed by six Death Eaters during what was supposed to be a routine patrol in Diagon Alley. James is hit by an unknown curse that nearly kills him, and they rush him to Remus and Mary's flat where Marlene McKinnon manages to heal him after a tense and desperate struggle. Dumbledore arrives and reveals that Dorcas Meadowes has been killed and confirms Sirius's suspicion that there is a spy within the Order of the Phoenix.