What a wonderful start to this new series. I loved the subtle allusion to Vivaldi's "Four Seasons" in the title/theme of this book/series - but then Josh has shown us, in various books, that he has an extensive handle on classical music. I chuckled at the humor interspersed throughout the book - sometimes snarky, sometimes gentle - but always most apropos to a particular situation between the main characters - a hallmark of his writing. And while I do not normally seek out paranormal stories, this little gem (and presumably those to follow) gave me much reading pleasure and made me really and truly want to believe in ghosts and troubled spirits and things that go bump in the night. And finally, I would be completely remiss if I didn't mention what a kick I got out of seeing the appearance of Stephen and Mark from his "I Spy" series, a special favorite of mine. Hopefully we will see more of them in future books - I have a strong suspicion that Mark, in particular, could help Kirk with some of the demons that seem to haunt him.
There is one very bleak pronouncement by Flynn that wrenched my heart and by the end of the book I was not certain that this issue had been resolved. Most likely it has not and I look forward to how Josh, and his two MCs, deal with this in future books.
All in all - another outstanding piece of writing by my favorite author!