Invited by their club's first female member Arima Maria, Egami and Arisu go on holiday on her uncle's solitary island resort. Her grandfather, from whom her uncle inherited the island, loved puzzles and also created one before his death, which lets you find his heritage in the form of diamonds once you solve it. While the students ponder on the meaning of the numerous Moai statues scattered over the whole island, 2 guests are found murdered in a locked room and the 2-way radio, the only way to inform the mainland, has been smashed up...
What an improvement! I am downright satisfied and impressed. Arisugawa stuffed so many puzzles into this work that after the relatively tight introduction there simply is not any sort of anticlimax. The reader finds himself in a huge swirl of numerous deduction issues and red herrings, that makes the whole reading process very enjoyable and the mystery very challenging. Again I felt defeated when the challenge to the reader came up, regardless of the totally logical and fair solution that followed.
The locked room wasn't that awesome, but Arisugawa also indirectly comments on that matter using his detective figure Egami Jirou, but it still was handled in an interesting way where it was more important why this locked room ensued. As in the previous work no one has an alibi for any of the crimes and there are plenty of possible motives and red herrings so you can only come to the solution when you combine all the puzzle pieces using the right method. It is indeed challenging but presented in an absolutely fair way with sufficient clues as long as you remember everything correctly (which is required in any good mystery novel though).
What also improved in my opinion was the characters' interaction. Maria definitely was a lovely addition to the cast and she fits in perfectly so it's already fun enough to listen to their dialogues and deductions. Yes, Egami serves as the detective figure, but the other characters, especially Arisu and Maria, aren't dumb either and that's another point I found very pleasant. Furthermore what mostly bugged me in the previous novel was that since the cast consisted of 17 students, most of them didn't feature a distinct personality and at the beginning it was kind of a nuisance to keep in mind who's who. This time the cast consists of both students and other adults each having a different background while being acquainted to or being a part of the family, which leads to different personalities that make the dialogues more diverse and interesting. On top of that, I thought the outcome was very sad... and lasting at that. Which made me glad that I already ordered the other 2 books in this series since I want to know how this develops.
What I also realized this time is that Egami is a somewhat unique detective figure. While he certainly is self-confident he never really acts arrogant towards other characters like most of the classical detectives do and he even asks for approval, critique or even if his theories make sense for others. He does stand out and everyone recognizes his intellect, but he is not an antisocial character. I thought his nature was conveyed as pretty personable and refreshing, which is favorable in this kind of settings and considering most classical detective figures tend to be the opposite and therefore might become too typical even nowadays.