Mark Collins built his life on a foundation of quiet pride. His house, his career, his beautiful wife, Sarah?they were the pillars of a fragile masculinity he protected at all costs. Their marriage was a comfortable, predictable fortress against the world.

But when a financial crisis forces them to rent out their downstairs apartment, the man who moves in is not just a tenant. He is an invasion. Marcus is a force of nature?a man radiating a quiet, dangerous power that exposes every crack in Mark's life and awakens a restless hunger in Sarah.

The arrangement is simple: Marcus's rent will be their salvation. But the unspoken terms are far more costly. Mark is demoted from husband to groundskeeper, from partner to observer in his own home. Sarah, caught between a husband she pities and a man she craves, begins a terrifying transformation from a restless wife to the star of a private, depraved performance.

Forced to become the silent audience for his wife's sexual awakening, Mark's only job is to listen through the floorboards. But as Marcus's control expands?moving from the basement to their living room, from secret encounters to open displays?the lines between spectator, accomplice, and director begin to dissolve. To survive, Mark must embrace a horrifying new role, not just watching the show, but helping to produce it.

Trapped in a suburban prison of their own making, Mark and Sarah forge a dark, new partnership built on shared shame and intoxicating humiliation. But in a world where the only intimacy left is the clinical debriefing of an affair, the greatest danger isn't the man who moves in downstairs?it's the monsters you become to let him stay.