Sir Thursday (The Keys to the Kingdom, Book 4)
Garth Nix
Get ready for more brilliant page-turning fantasy from master, Garth Nix. On the fourth day there was war! Pick up with Arthur Penhaligon as his Keys to the Kingdom adventures continue in the mysterious House.
Reviews

It was really good and I liked Arthur the best
Don Leach Hungry-Hippo 30.09.2023

Arthur has been forced o joined the Army. He searches everywhere for Sir Thursday, owner of the 4th key. But... Arthur has been washed behind the ears (mind wiped). This book has more and more suspense every chapter.
Anonymous 01.08.2020