Time-travel, smugglers, arsenic — what’s not to like in Sally Gardner’s novel for teenagers?

Which of us, as an adolescent, did not experience at some point a terrible sense of not belonging? Which of us did not yearn for a door to open into a place entirely elsewhere? At that liminal time in our lives, we constantly search for new thresholds, over which we might find ourselves — or another.

For most of us the door lies in our imaginations; for A.J. Flynn, the hero of Sally Gardner’s striking, elegant new time-travelling novel for young adults, it actually exists, in the unprepossessing environs of the post office centre in Mount Pleasant. A.J. is the heir to a key to a door which leads backwards and forwards from the 19th century to the present; he is also the only person who can lock it. Thus a dilemma is neatly set up: does A.J. continue to allow intercourse between the two times, so that the lost can be found, and those who want to be lost can’t be found? Or does he close the door — and therefore the potential for wonder and riches — for ever.