Peter Higgins writes about the challenges bringing together the colliding thriller genre and fantasy genre elements -- from structure to pacing to fantastic vs realistic in his Wolfhound Century trilogy fantasy modeled on Soviet Russian history.
As an example of what Higgins learned:
I soon realised it wasn’t just the diverse story elements that were in constant creative tension, it was the genres themselves. Fantasy and thriller are two distinctly different ways of thinking and imagining. They stretch and tear and illuminate each other, and I was constantly working to keep them in balance. Thriller wants to press on and keep the tension high, fantasy wants to linger and explore; thriller wants to end decisively, fantasy wants to go on expanding forever. . . .
Free imagination versus rules and control: that’s one way of conceiving the collision between thriller and fantasy. Thriller is about the logic of conventions: plot, believability, recognisable character types, mysteries that have hidden solutions, resolutions waiting to be uncovered. As a writer of thrillers, you have to follow the rules or it just doesn’t work. Fantasy is otherwise. A fantasy story, once it announces itself as such, can do anything it wants. It can say anything and go anywhere. Bring back the dead. Cure any sickness. Animate any inanimate thing and give it a voice. In fantasy, you can take any pleasure you like from anything you can think of. I found that fantasy wants to break thriller apart: it wants to split the carapace, disrupt the predetermined plot machine and crack open an inexhaustible well of narrative possibility. Refreshing and repurposing, fantasy unlocks the strangeness, plenitude and imaginative wealth inside the thriller world.Beyond this, however, Higgins goes on to explicate why he thinks these two genres together are successful in his work because the religious, political and cultural history of Russia are by heritage used to the fantastic insertion into the daily mundane reality. In other words he didn't just go, o wouldn't it be cool to have zombies run around in Elizabeth Bennett's village! Which doesn't work for a satisfying reading experience, but instead is so preposterous as to be stupid -- unlike Wolfhound Century -- because that's not how that culture and history behave -- as Austen herself illustrates in Northhanger Abbey.
The three volumes are titled Wolfhound Century (2013), Truth and Fear (2014) and Radiant State (2015). Published, I believe, by Orbit UK and Orbit U.S.