A Dog's Breakfast (2007)

Patrick (David Hewlett) finds his quiet but comfortable life disrupted when his sister Marilyn (Kate Hewlett) brings her new fianc, Ryan (Paul McGillion) - the star of a popular science-fiction TV series - home for a holiday visit. A misunderstanding leads the suspicious Patrick to believe his sister's life is in danger. But when someone else accidentally turns up dead, an increasingly frazzled Patrick, with the help of his faithful dog Mars, tries to keep his sister from learning the truth.