What if the world holds more dangers--and more wonders--than we have ever known? And what if there is more than one world? From Heather Dixon, author of the acclaimed Entwined, comes a brilliantly conceived adventure that sweeps us from the inner workings of our souls to the far reaches of our imaginations. Jonathan is perfectly ordinary. But then--as every good adventure begins--the king swoops into port, and Jonathan and his father are enlisted to find the cure to a deadly plague. Jonathan discovers that he's a prodigy at working with a new chemical called fantillium, which creates shared hallucinations--or illusions. And just like that, Jonathan is knocked off his path. Through richly developed parallel worlds, vivid action, a healthy dose of humor, and gorgeous writing, Heather Dixon spins a story that calls to mind The Night Circus and Pixar movies, but is wholly its own.