The phrase "thriller territory" refers to a place, situation, or topic that is suspenseful, exciting, and full of suspenseful action or unknown dangers. Full definition
Reworking his own un-produced stage play, Finley moves fluidly into thriller territory, as the girls» relationship skips straight from strained friendship to something darker. (avclub.com)
But his latest project will see him venture into psychological thriller territory with one of the Paradise Lost... (avclub.com)
Wilson, however, has plunged into psychological thriller territory before, including with psycho - sexual twists. (torontosun.com)