Mysterium: The Palace of Memory: Book 2 by Julian Sedgwick
Danny Woo has escaped from the jaws of death once - but his trials are not yet over. He's meant to be recovering, but when he discovers the Mysterium - the circus into which he was born, and which cost his parents their lives - is being reformed in Barcelona, he determines to join them. But all is not well - who is the bad seed inside the once-loyal company? And who is the woman in green who can kill, and who seems to be trailing Danny with each move he makes? Everything, he knows, is linked to the death of his parents: he must continue his quest to find his parents' killers. Once again, the story culminates in Danny's participation in a well-known and dangerous stunt.