The Necromancer is the sequel to the Sorceress. Josh, Sophie, and Nicholas meet up with Perenelle. Sophie is kidnapped by Aoife, Scathach's twin sister, who wishes to know where her twin went. Aoife takes Sophie to her friend Niten's house, where the rest of the Flamel group go. The two "groups" resolve their problems. They ask Prometheus to teach Josh Fire Magic, which he does. Mars helps Dee enchant josh to come to him. Dee makes Josh a necromancer and orders him to raise Coatlicue, mother of all gods, an Archon. Dee puts a spell on Josh to make him think Coatlicue is incredibly beautiful. Sophie, Aoife and Niten arrive, and fight Virginia Dare, an immortal who makes a deal with Dee, Dee, Josh, and Coatlicue. Sophie attacks Coatlicue, which shocks Josh, because of the spell Dee placed on him. Aoife pulls Coatlicue and herself back into the portal where Coatlicue first came from, telling Sophie to tell Scathach that she di d this for her. The Dee group leave the Flamel group to die. Meanwhile, Joan of Arc and Scathach are pulled into a portal to a Shadowrealm. and are soon joined by Palamedes, Shakespeare, and Saint-Germain. The hook-handed man, Marethyu (name meaning "death") time travels back in to the time before Danu Talis sank.
You should read the three books before this one to know about some of the things I'm talking about in this summary. -Albert