Here's the synopsis:
"Tamzin Pook is a fighter in the Amusement Arcade. And what she does best is killing Revenants.
All she knows is survival, having arrived in the Arcade as a small child. She pushes away her memories, her hopes, and her fears, and she emerges into the arena to battle the Revenants--dead brains nestled in armored engine bodies. She doesn't dare to hope or wish for anything more than to survive another day.
Meanwhile, the wheeled city of Motoropolis has been taken over by a rebel faction who killed its leaders and commandeered the city. Its only hope is a teacher named Miss Torpenhow who's determined to find the Mayor's good-for-nothing son and force him to take back what's rightfully his. But to get to him, she'll need to find someone who's skilled at fighting Revenants.
With a daring abduction, Miss Torpenhow and Tamzin Pook's destinies are entwined, and so begin their adventures together...
This stand-alone Mortal Engines novel follows an unlikely crew of fighters-turned friends: Tamzin Pook, Hilly Torpenhow, mayor-to-be Max Angmering, and washed-up mercenary Oddington Doom. Together, they must find a way to outwit the assassins that are determined to drag Tamzin back to the arcade, and try to take back Motoropolis."
Thunder City is a PREQUEL of sorts per Reeve:
"The rule I set for myself when I was writing this one was that it shouldn’t feature any of the people or places from previous Mortal Engines books. So Thunder City takes place just over a century before the original book, when the town-eat-town world of Traction Cities is slightly less ruthless than it will become later, and none of the characters from the original quartet has even been born yet. (I suppose Mr Shrike must be bimbling about somewhere, but he’s still just yer basic implacable killing machine at this point so there’s not much point in paying him a visit). So hopefully this new take will be accessible to people who’ve never read Mortal Engines, and hopefully people who have read it will enjoy an adventure set in the same world."
One can pre-order on Amazon now for a September 2024 release.
Note there is a sequel to this prequel, Bridge of Storms
