Yellowstone's spinoff Marshals revealed heartbreaking details about Monica's last days after her offscreen death. During the Sunday, March 15, episode of the hit CBS series, Thomas (Gil Birmingham) spoke with Kayce (Luke Grimes) about his last wife, saying, "I saw Monica's shoes by the door. I'm guessing that's her horse terrorizing your ranch." Kayce noted that he bought Monica a stallion "a couple weeks before she got worse." " Took a while to tame it out of him.