If you’ve read any of the Laundry books, you’ll want to read the first chapter of the latest book in the series here.
If it follows the formal schedule, the book will go on sale on June 23rd in the UK, and the 28th in the US and Canada. You may see it offered a bit sooner in a few locations, depending on the vagaries of the book distribution system (and some retailers’ inability to keep to publication dates).