Complete Unknown is Marston's first English language film and centers on Tom (Shannon) and a mysterious woman named Alice (Weisz). When Tom and his wife host a dinner party to celebrate his birthday, one of their guests brings a date named Alice. Tom is convinced he knows her even though she's going by a different name with a different biography, and she's not acknowledging she knows him. We soon find ourselves on an all-night odyssey with two characters, one needing to make a change in his life, the other questioning how to stop changing.