1 The 78-Storey Treehouse ANDY GRIFFITHS & TERRY DENTON, PAN, $14.99 That wacky treehouse continues to grow and delight.
2 Harry Potter and the Cursed Child J. K. ROWLING, JACK THORNE & JOHN TIFFANY, HACHETTE $45 Eighth adventure, a play, for the now middle-aged boy wizard.
3 Ghost Empire RICHARD FIDLER, ABC BOOKS, $39.99 Rattling history of the Byzantine empire.
4 Black Rock White City A.S. PATRIC, TRANSIT LOUNGE, $29.99 Winner of this year's Miles Franklin award.
5 Nutshell IAN MCEWAN, JONATHAN CAPE, $32.99 McEwan reworks Hamlet from an unlikely point of view.
6 Truly Madly Guilty LIANE MORIARTY, MACMILLAN, $32.99 Something goes terribly awry at a family barbecue.
7 Our Souls at Night KENT HARUF, PICADOR, $19.99 Moving tale of elderly couple finding some sort of love.
8 The Course of Love ALAIN DE BOTTON, HAMISH HAMILTON, $32.99 Philosopher returns to fiction, with added advice.
9 Mega Weird: WeirDo ANH DO, SCHOLASTIC, $14.99 Seventh in the comic adventures of young WeirDo.
10 How it Works: The Dad JASON HAZELEY & JOEL MORRIS, MICHAEL JOSEPH, $19.99 Latest spoof of the Ladybird books for children.
Nielsen BookScan, week ending September 3.