What if an Earth-mass rogue planet — the Moon Thief — swept through the inner Solar System on an unbound hyperbolic trajectory? Earth, the Moon, and the Sun start in their real 1 January 2025 configuration. The Moon Thief begins far from the Earth–Moon system, allowing the Moon to complete a full, undisturbed orbit around Earth. Roughly thirty days in, the interloper closes in and strips the Moon away in a chaotic three-body exchange. Rogue planets — free-floating worlds ejected from their birth systems — may number in the billions in the Milky Way. While a Moon-stealing flyby is extraordinarily unlikely, it illustrates how fragile the Earth–Moon bond is against a sufficiently massive and well-aimed intruder.