Thomas MacLaine is a deputy in the small town of Greenvale during the events of Deadly Premonition. An excellent baker, Thomas' biscuits are highly regarded by many, including FBI agent Francis York Morgan. Thomas also cooks and mixes drinks at the Galaxy of Terror, a jazz bar owned by his sister, Carol MacLaine.
Thomas has an acute love for squirrels, taking the liberty to attach a variety of squirrel key-chains to the various keys around the police station to help differentiate them. On rainy evenings, he holes up in his apartment, a well-kept room connected to his sister's much messier suite, and listens to jazz records.
It is eventually revealed that Thomas, alongside Carol, is an accomplice to the New Raincoat Killer, George Woodman. Carol and Thomas are revealed to be in love with George, who views them as little more than substitutes for Emily Wyatt, whom George was rejected by. Following York's discovery of the Galaxy of Terror's hidden back-room, Thomas, wearing a red dress and wig, knocks him out and takes him to the clock tower.
As Emily, Forrest Kaysen, and Kaysen's dog, Willie, track York's scent, York seemingly takes pity on the MacLaine siblings, attempting to convince Thomas to free him and leave town. Thomas is appreciative of York's gesture, despite going on to explain that it is too late for them to leave. Upon reaching the clock tower, Emily finds herself in a fight with Thomas. Although Emily wears Thomas down and attempts to convince him to give up, she's cut short by Willie jumping into the room, leading Thomas to accidentally get stabbed before falling face-first onto a sharp hook.
Although Deadly Premonition leaves it ambiguous whether Thomas' character is meant to be that of a homosexual cross-dresser or a transgender woman, it is implied to be the latter. This can be seen in York's internal remarks about Thomas' effeminate behavior, the raised pitch Thomas speaks in during the clock tower scene, and the fact that Thomas accompanies George's victims as a spirit near the end of the game, dressed similarly to the other goddesses of the forest.