1. From Wikipedia:
"When Julius Kane tries to summon Osiris through the Rosetta Stone in the British Museum, he also releases Set, who seals him in a coffin, as his children Sadie and Carter Kane watch. He also releases the other children of the Demon Days: Nephthys, Isis, Horus, and Osiris. The British police come to Carter and Sadie's grandparents' home, as Carter is with Sadie because of the twice-a-year visit, and question Carter and Sadie. Amos Kane, the children's uncle and Julius's brother, brings them to the family mansion in Brooklyn. That night, Carter's soul (known as a ba), travels to Phoenix, Arizona, where he sees Set, and learns that he will summon an extreme storm on his birthday. The next morning, Carter and Sadie describe what happened, and Amos tells them he will go search for Set for more information. He also tells them not to go to the library but disobeying him they decide to go into the library anyway. While in the library, Set's warriors attack the house and Bast the cat goddess, who is disguised as Sadie's cat, Muffin, saves them. She is later overcome by Serqet, the scorpion goddess. They soon meet Zia Rashid who helps distract Serqet while Sadie and Carter escape through a portal. Zia takes them to the House of Life, to be trained as magicians. Once the Chief Lector Iskandar, dies, and is replaced with Desjardins, the Kanes have to flee again, as the House of Life see them as a threat, as they host the gods Horus and Isis. They go to Paris to retrieve a book which tells them how to defeat Set. They find out that they need the Feather of Truth to help defeat Set so they then go to the underworld to retrieve the Feather of Truth from Anubis. On the way out they are attacked by Sobek the crocodile god but they escape when Bast sacrifices herself to save Carter and Sadie. Desjardins calls upon Sekhmet, the lion goddess, but Zia saves them with the help of their uncle. Then, Carter and Sadie go to the Red Pyramid in Phoenix. While Carter and Set battle each other, Sadie performs a spell that transports the pyramid to Washington, D.C. However, before she can seal the spell, Sadie spots Apophis, who was going to use the red pyramid to escape the Needle. Apophis has been close to doing this for quite a while, but with all the chaos that would be caused by the storm released by Set he will find an opening. After forcing Set to join their side to stop Apophis from escaping into the world, Zia is revealed to be a shabti. Carter and Sadie must show Desjardins that they are not a slave to the god they are hosting. To do this they both release the gods, but some of the gods' essence go into their amulets. Julius decides to stay in the Underworld as Osiris with their dead mother, Ruby Kane. Horus and Isis reward them by repairing the rest of Amos’s house and reviving Bast. Carter and Sadie then use the djed amulet to recruit others to their cause. This amulet will attract those who have the blood of pharaohs."
I'm sorry but the other summaries are copyright protected so I can only give the summary from wikipedia, which not very detailed. I'm still reading the book so I can't still tell you fully.