Christine Montgomery is the main antagonist in the movie View From The Top.
She starts as Donna's friend and co-worker at a small airline. The two of them move up to the prestigious Royalty Airlines, and Donna aspires to be assigned to the Paris first class route. Christine switches her flight attendant exam with Donna's, resulting in her getting a New York route assignment, while Donna is based in Cleveland.
When Donna discovers that Christine switched the exams and has been stealing from the company, she arranges for an auditor to be placed on her flight, who catches her stealing again. Christine is fired and arrested, but not before spitefully admitting to switching the exams and claiming that she was justified in doing so because she envied Donna.