Which opens with Amelia describing how the other four title characters regard the southern boundary they are not allowed to pass: Colin says it doesn't exist, the forest goes on forever; Quentin says it's the Old Road; Victor says it's the highway; Vanity says that it doesn't exist unless they admit it does -- just like she's not the Queen of England because people don't say she is. . . .
There are strange things about their school. Mrs. Wren hold birthday parties for them at irregular intervals. When Victor tries to reproduce the Michelson-Morley experiment, it shows a difference in light-speed, but when Amelia tries it in his absence, it shows none. Quentin says he can fly. They find documents -- in Amelia's handwriting -- that she doesn't remember writing, about their Tales which they don't remember telling. And, when they all wish to be adult and able to leave, the Board of Governors meets.
When spying on them, Amelia and Quentin learn that they are being held hostage by the Greek gods. To have Mavors (a.k.a. Mars) open it by announcing that the children are not to be killed is -- somewhat less than reassuring. And since Zeus is dead, Olympus is rife with factions about who is to ascend the throne, and what is to be done with their hostages. They appear to be coming to the conclusion that they ought to be split up.
Hmmm. The trilogy has the same basic structure as The Golden Age. First book: character(s) with inflicted amnesia tries to figure out what's going on. Second book: characters try to sneak about to avoid being overwhelmed by what was discovered in the first book and get to a situation where more is possible. Third book : Do something about it.
Which is a structure that can accommodate rather different stories. In these books it can also accommodate a siren who is the last of the Donatists, a spaceflight to the planet Mars, two deserted islands (albeit only one significant one), Hollywood, four, five, six dimensions, sailing a magic boat through dreamland, an astounding amount of Greek mythology, more than you will find in your typical "Greek mythology" book, mixed in with plentiful other references such as Beowulf -- did you know that he didn't kill Grendel's mother, who went to the Destroyer aka Apollo, who sent the dragon? -- and Mother Goose, and it all melds together, dream communication, and nanites.