The core engine of Significant Mother Season 1 is an absolute nightmare scenario for any young adult. The story unfolds in Portland, Oregon, centering on Nate Marlowe, a budding, somewhat tightly wound restaurant owner. Nate’s life is completely upended when he returns home from a business trip to discover that his charismatic, carefree best friend and roommate, Jimmy Barnes, has started sleeping with Nate’s newly separated mother, Lydia Marlowe.