Author Will Kostakis returns to face time travel, unexploded bombs and a tangle of timelines in Terry Pratchett's final Johnny Maxwell book from 1996, Johnny and the Bomb!

When Johnny and his misfit friends look after homeless eccentric Mrs Tachyon's shopping trolley, they soon discover she has a complicated relationship with time. Johnny, Yo-less, Wobbler, Bigmac and Kirsty travel back to World War II, on the eve of the "Blackbury Blitz". Johnny knows bombs are meant to destroy Paradise Street - but can he and his friends do anything about it? Do they even have the right? And how will they get back ho- hang on. Where's Wobbler?

Pratchett's first book focussing on time travel also touches on the worries of teenagers, local history, racism, sexism and the nature of fate and destiny. It might seem weighty for a children's book, but children think about this stuff all the time! Did you follow all the time travel shenanigans? How do you think Pratchett's handling of these issues compares to modern middle grade fiction - or even his own previous Johnny books? And if you could go back in time, would you try and change things for the better? Join the discussion using the hashtag #Pratchat37.

Returning guest Will Kostakis is a writer and award-winning author. Since we last saw him in #Pratchat18, "Sundog Gazillionaire", he's published his first fantasy YA novel, Monuments, and its sequel, Rebel Gods. His new novella, The Greatest Hit, is out now from Lothian Children's Books as part of the Australia Reads initiative. Find out more about Will at willkostakis.com, or follow him on Twitter at @willkostakis.

You can find the full show notes and errata for this episode on our web site.

As mentioned at the end of this episode, the fiction anthology Collisions from Liminal Magazine is out now, featuring Liz's story "The Voyeur"! Order it from your local bookshop. And we also announced that the Australian Discworld Convention in Sydney has had to be postponed from 2021 to 2022. Find out more at ausdwcon.org.

Next month we see out the year with a favourite, as we time travel about ten Discworld books ahead to meet Moist von Lipwig in Going Postal! We've invited two experts on con artistry to discuss it with us: writer and magician Nicholas J Johnson, and comedian and actor Lawrence Leung! Get your questions in via social media using the hashtag #Pratchat38.