Mary is the wife of Douglas, a wealthy US presidential candidate, and mother to their daughter, Julia. She publicly confronts her husband for refusing to abandon his campaign after the Nostradamus Sect kidnaps Julia, declaring to a crowd during the World Cup opening that he prioritizes his political ambitions over rescuing their daughter. Throughout much of the film, Mary remains skeptical of Douglas's love for Julia, observing his coldly calculating assessment that the kidnappers won't harm Julia due to her value as leverage. Her perspective shifts when Douglas abruptly leaves a critical campaign event upon learning the Nostradamus Sect has taken Julia to the explosives-rigged Douglas Tower. Witnessing Douglas choose Julia's safety over his political ambitions leads to reconciliation between them, culminating in their emotional reunion with Julia after Lupin III rescues her. Mary is documented only within this film across Lupin III media.