“White Lie” is something of a misnomer, given that the fraud that Katie (Kacey Rohl), a young college student, is perpetrating is far from victimless. Neither is it easy: The effort involved in pretending to have cancer consumes most of her energy (and all of the film’s 96 minutes). She looks exhausted, although — according to a crooked physician — not nearly enough to convince potential marks. Luckily, that’s a problem weight-loss medication can solve.

Small in scale and gray in aspect, “White Lie,” written and directed by Yonah Lewis and Calvin Thomas, is a coolly indeterminate tease. Instead of a third act, this unusual Canadian drama simply continues Katie’s desperate sprint to stay one step ahead of exposure, and her frantic recalibration whenever her scam is threatened: A grant application requires falsified medical records; a social-media post demands panicked damage control.

The plot’s repetitive rhythms are eased, though, by Rohl’s startling commitment to her character’s pathology — a long, money-grubbing con of begging, borrowing and online fund-raising. We first see her in her bathroom, meticulously shaving her head, the cold calculation of her actions contrasting with the practiced sweetness of her public persona. Katie’s estranged father (Martin Donovan) may challenge her ruse with hints of a troubled past; but her affluent, devoted girlfriend (a wonderful Amber Anderson) is pitiably eager to finance nonexistent treatment options.

Yet as Katie veers from pathetic to vicious, “White Lie” observes her shameless behavior without attempting to elucidate. The result is a movie that’s too vague to capitalize on its jittery tone and too timid to fully wrestle with the monster at its core.

White Lie
Not rated. Running time: 1 hour 36 minutes. Rent or buy on Google Play, FandangoNow and other streaming platforms and pay TV operators.