Once the assistant to a great detective, Kimihiko Kimizuka took on a challenge Siesta bequeathed to him after her death and arrived at a conclusion that surpassed his wildest expectations. To bring back the great detective—the stuff of miracles—Kimihiko and Natsunagi fly to London yet again to obtain evidence that can bring down Seed. On the flight there, however, he hears the same words as he did four years ago: “Is there a detective on the plane?”
To revive Siesta and stop Seed, Kimihiko, Nagisa, Char, and Yui all take different actions. Kimihiko and Nagisa's plan is to go to London. There, they want to meet the tuner, "Priestess," and find clues about how to defeat Seed. The "Priestess" is able to see in the future, so perhaps she knows clues about how to revive Siesta.
Then, Char is training her physical abilities under Fuubi while Komori gives special training to Yui, in order to awaken her "seed." All these individual actions are very essential, so everyone desperately tries to fulfill their tasks. However, Seed isn't that kind; indeed, he won't wait for them to finish their preparations. Since everyone's in different locations, the worst disaster may end up occurring. Perhaps, it might be the worst future that the "Priestess" predicted. ーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーー I think this series is special. While this is an SF light novel rather than a mystery one, the plot and developments are more than enough interesting. The next development may seem really predictable, but in reality, it is actually very surprising. To me personally, that last scene was very compelling.
Additionally, while the entire story is very middle school syndrome-ish, the novel still has a strange appeal to it. As a result, I rate this novel as a 5.
The series is somewhat confusing. It might be better, if I read all of the preceding novels closer together. The protaginets are still trying to solve the detective last riddles, bring back the detective, and fight SEED.