I really enjoyed The Rise and Fall of DODO, coauthored by Nicole Galland and Neal Stephenson, and this sequel, written by Galland, stays true to the first book's DARPA + time travel + witches + quantum physics vibe, but throws in Shakespeare and ancient Romans for good measure. Grainne raises the stakes in her bid to eliminate technology and thereby save magic, while the rogue DODO agents need outside help to thwart her plans.