Guided by the noise of a great many voices all talking together, and passing the girl in his impatience, before they had ascended many steps, Ralph quickly reached the private sitting-room, when he was rather amazed by the confused and inexplicable scene in which he suddenly found himself.
There are no more uses of "inexplicable" in the book.
Show samples from other sources
With that he turned away and once again started inexplicably walking toward the wall.
James Dashner -- The Scorch Trials
For some inexplicable reason, those words popped into Thomas’s mind.