truthfully? I think the answer was grounded in my first steps writing it. The online instructor is an editor at an imprint of Harper and Bray and before we started, she asked that we post ideas. I posted seven and she liked this one. "DaVinci Code style young adult with magic. Brother (11) and sister (15) arrive in Rome to find their parents missing and people are dying in ritual killings at famous sites in ancient Rome. Tenacious Eve must find and solve the clues and gain control of her new powers to reunite their family against a ticking clock. Oh and add in a 17-yr-old boy, whose father is also missing that joins the hunt."
I'll never write another book without first writing a catchy commercial premise that is interesting, different, and timely.
And no, neither of us had any idea that Angels and Demons was being made into a movie until half way through the class. I figured it doomed the book, but I persevered anyway. I use only two locations from Dan Brown's book, but how do you avoid St Peter's and Castl Sant d'Angelo--the others are all different and the final confrontation takes place at the Pantheon, which includes the Pieta, the goddesses Minerva and Isis, St Michael, martyrs, and a Narnia style battle between 4000 skeleton army raised from the Church of the Bones and reanimated lions, tigers, bears, gladiators from the Coliseum. Oh--and the open roof of the Pantheon is a gate to heaven and in Michelangelo's mystically completed sphere of the Pantheon in the mirror image is a gate of hell that will be opened unless Eve figures out the last piece of the puzzle.
All the sites make a pentagram (really!) and the Pantheon is in the exact center, all with obelisk's from Isis' temple. Definitely needs a map to go with the book. All have ties via art and history to Michelangelo... Yeah--tossed in everything but the kitchen sink and frankly the rituals are really gruesome.