Claim: Part of Raising Cain's plot is when Julia finds Nix Sr. holding Amy hostage as part of his control group to study the development of MPD.
Evidence: Jenny follows a woman who she thinks is Waldheim to a motel, but it is actually Carter/Cain. She follows Carter/Cain, who is now Margo, into an elevator. When it opens, she sees Nix Sr. holding Amy hostage.