A link to the summary of "The Alexandria Quartet" and other information can be found at the eNotes link below. Here is an excerpt regarding the first volume and character, Justine (1957):
Justine seems, by turns, exotic and passionate, nymphomaniacal and sexless unless sex is yoked with political intrigue. Readers may think they know her when they understand that her sexual activity amounts to an attempt to exorcise the fact that she was raped as a child. Or, when one realizes that all of her sexual encounters may be rooted in espionage, one is invited to conclude that she is merely Nessim's spy, a tool in her husband's anti-British conspiracy. Even her psychoanalysts are unable to discover the one true face behind the multiple masks.
Of course, as readers work their way through the simultaneity of the complete Alexandria Quartet, and learn that the basic facts of the first volume are a kind of hoax, readers finally come to understand, with Darley, the romantic young narrator in the process of learning how and what to see, that Justine does have one identity, one face: "the primitive face of mindless Aphrodite."