The titles, covers, and summaries for Adventures #23, Mystery on the Mayhem Express (https://www.amazon.com/Mystery-Mayhem-Express-Hardy-Adventures/dp/1534478078/ref=as_li_ss_tl?&linkCode=ll1&tag=hardboyscasee-20&linkId=5874c9d1e2cb07e4243c701bfb301533&language=en_US), which has a release date for June 22, 2021 and Clue Book #14, The Bad Luck Skate (https://www.amazon.com/Luck-Skate-Hardy-Boys-Clue/dp/1534460217/ref=as_li_ss_tl?&linkCode=ll1&tag=hardboyscasee-20&linkId=975379977ce32732f0ebd8061c377661&language=en_US), which has an August 17, 2021, release date, are both now starting to show up at various online retailers for pre-order.
(https://www.hardyboyscasefiles.com/images/comingsoon/HBA_023.jpg) (https://www.amazon.com/Mystery-Mayhem-Express-Hardy-Adventures/dp/1534478078/ref=as_li_ss_tl?&linkCode=ll1&tag=hardboyscasee-20&linkId=5874c9d1e2cb07e4243c701bfb301533&language=en_US) (https://www.hardyboyscasefiles.com/images/comingsoon/CB014.jpg) (https://www.amazon.com/Luck-Skate-Hardy-Boys-Clue/dp/1534460217/ref=as_li_ss_tl?&linkCode=ll1&tag=hardboyscasee-20&linkId=975379977ce32732f0ebd8061c377661&language=en_US)
Mayhem Express sounds like a poor mashup of the original Mystery of the Flying Express, Terror On Track, Mystery Train & Last Train To Blue Moon Canyon.
I haven't even read Treacherous Tide yet.