Nicholas is taken from the Orphanage – a terrible place run by the intimidating Matron – to live in a castle (where exactly this is, he has no idea) where he is cared for and finally has enough to eat. His new guardians, Ranik and the rest of the Synod, have some purpose for him that he has yet to discover. Nicholas has learned a few things from his time in the Orphanage – keep quiet, stay out of sight, and don’t let on that you know anything. Somehow he manages to keep secret the fact that he understands his keepers’ language. They continue to address him in English when they want him to know what they are talking about, and speak in their own language when they do not. And so he learns that he is someone important to them, and that they want to get some secret from him, from his mind. And that they are running out of time. Nicholas’ other discovery is the library that lies beneath his room. He sneaks down there during storms and teaches himself to read, increasing his experience of the world. He learns how his captors keep watch over him, he learns that they can’t see him without electricity.
Then they start giving Nicholas the truth serum. It’s supposed to make him tell them what they want to know. But he’s blocked somehow. Or they aren’t asking him the right questions. All he can tell them is that there’s a dog, and his name is Wuffy. And he was a BAD DOG. One of the keepers, Wark, believes that he can do more with Nicholas. But he is kept from him, as his methods have killed his other victims. The Synod grows impatient, however, and one last effort is made to unblock Nicholas’ mind – they bring in a girl, Lark, who lives on the streets. She is hired to pump him for information. But she’s not that attached to her keepers either. She and Nicholas become friends, and when Nicholas learns that they are going to kill Lark and then use a machine to extract what he knows (which will kill him) he convinces her that they must escape. They are tracked, but manage to throw off their pursuers several times.
Nicholas has brought a book along with him from the library – the story of a dog named Wuffy. In his final moments at the castle he has an insight into what the Synod wants from him, and the book has the answer. His mother left him a message written into one of the illustrations that tells him where in the book he can find the “formula” that the Synod is seeking. She also gives him the name of a man who can help him. Nicholas discovers the formula and then destroys the page that holds it. He does not mention it to Lark, so that if they are recaptured, she won’t be able to tell the men anything. They manage to find safety with the man who Nicholas’ mother names. He takes them in as his own children, but Nicholas never reveals the formula to anyone.
Now, Nicholas is actually Nicholas Tesla, and I don’t know enough about the real Nicholas Tesla to say what the formula might have been – although I’m intrigued. The story ends a bit too nicely – in that the kids are suddenly safe, and wow, that’s it. There’s an epilogue that describes how some of the bodies of the Synod men were found, others whereabouts are unknown. Some additional wrapping up might have been useful. Still, an intriguing mystery.