If you've read Adept, then you know just how strange life became when Susan Milton and David Braun got caught up in the theft of the Marker. One year later and it's still missing. With Professor Shaw to guide them, David and Susan are determined to find it first. But they must stay hidden because somewhere out there, the Marker's previous owners are hunting for it too - and they have an ally they don't even know about. Her name is Jo.
Jo Hallett has known the Professor all her life. She is ferociously bright, a brilliant researcher ... and a nightmare to work with. And she is about to make a mistake that will not only put the lives of everyone around her at risk, it will also bring something very dangerous into the world. If Jo can avoid betraying her friends or being killed by their absurdly powerful enemies, she might just solve a mystery that has defeated a hundred generations of fanatics. And all it will cost her is her life.