I received a beta copy of this book from the author, and I submit this review honestly and voluntarily.
Even though this novella has only just been published, the author's note at the front of the book places this as Cullen's series 1.5, and don't let the chosen cover mislead you, Cullen hasn't gone to the Wild West, it's the Wild West that's come to him via an American who hopes to make his living locally by way of his establishment the Grand Ole Opry.
The story does touch on a subject that seems to be very close to Cullen's heart and, though not fully revealed in the novella, relates to his prior love/partner. As a result, we see a hidden burning anger and need for isolation in Cullen that we haven't/don't see in Cullen in other books. I believe we will see more of the reason surface in future books.
Overall, another excellent story in the Cullen series. All of them are well worth reading. Hope there's more to come. 4-stars purely because it's only a novella.
Highly recommend.