Nate shows Henry where de Quincey’s hideout is, and Charlotte notifies the Enclave that they will need to attack that night. Will and Jem are not allowed to go on the mission because they are not yet 18, but they work with Thomas to prepare the weapons. While everyone prepares, Jessamine invites Nate to play cards. Tessa, put off by Jessamine’s suggestion that her brother gamble again, worries that he may relapse. After Charlotte and Henry leave, Axel Mortmain arrives at the Institute. Will and Jem meet Mortmain outside. He tries to offer them new information about de Quincey, but Nate has already given the Shadowhunters what they need to know. Mortmain tells the Shadowhunters that the Dark Sisters are performing the spell in a different location than the one Nate gave them, so Will and Jem leave the Institute to try to intercept the Sisters. As soon as Will and Jem leave the Institute, several automatons attack, killing Agatha and threatening Sophie and Tessa.

Meanwhile, Will and Jem arrive at the Dark Sisters’ house to find only Mrs. Dark, who is about to start a ritual to revive her dead sister, Mrs. Black. The Shadowhunters confront Mrs. Dark and demand to see de Quincey, who they believe is the Magister.