This was such a fantastic mystery, full of puzzle solving & great characters! The whole backstory of this house turned hotel, the people who used to live there & that set the rules that everything has to stay the same, to the female explorer we learn about-FASCINATING! SO atmospheric as well. This huge house/hotel with all of its history, secrets, & puzzles was so intriguing & just gave me all the cozy, mysterious vibes. Add in all the eccentric hotel guests staying the weekend-incredible! These 3 kids are all amazing, each in their own right. They each bring something crucial to the table to solving this mystery. POV go back & forth between the 3, so you get to see the weekends from each of their POVs & how different each experience is, & what each is doing to solve this mystery of this house. The codes & puzzles were so great! I loved that. I hate math, lol but I love codes & puzzles apparently. Anna is my favorite, because I would have been doing what she did. Exploring! Seeing things people hadn’t seen in many years….Such an amazing feeling that would be. I love history. The way the whole story/mystery came together & what all we find out was superb. There were twists, & I never guessed the ending. Such a heartwarming, book hug ending. What Anna did with what she found at the very end, & why-melted my heart. Goosebumps. Highly recommend this. Full of family, friendship, mystery, puzzles, codes, history, amazing characters, & great writing. Beautiful cover by Kat Lyons too!💜