Name of the book: Butterflies (The Secret Casebook of Simon Feximal #2)
Genre: MM Romance, Historical, Paranormal
Book publish year: 2013
Rating (out of 5): 4
Brief intro: Journalist Robert Caldwell is still smarting from his first encounter with ghost-hunter Simon Feximal. Their night in a haunted house was thrilling, but the aftermath leaves Robert hurt, disappointed, and resolved not to see Simon again.
But just a few days later their paths cross once more, this time investigating a pair of mysterious deaths: two corpses shrouded in butterflies.
Now Robert wants the truth – on the deaths, on where the butterflies came from, and most of all, on the attraction that still burns between him and Simon.

Review: Creepy, but very good. Even if it's not the fist in the series, you can start here (it's a freeby) and if it's you thing go ahead with the other ones, including the just released The Secret Case of Simon Feximal, that promises to explain lots, lots of things.