In many ways, an ending can make or break a movie. Think about a film like 2000’s “Pay it Forward,” a schmaltzy, sentimental drama about a child who inspires others to put good deeds out into the world with no expectation of anything coming back their way. In the hands of director Mimi Leder and led by strong performances from Haley Joel Osmont and Helen Hunt, the film manages to serve its purpose and tell a compelling story about being of service to others, all of which is undercut in its conclusion when Osmont’s 12 year-old character is stabbed to death at school. It’s a horrible, traumatic wrap-up for a film that otherwise preaches goodness, like having George Bailey in “It’s a Wonderful Life” fall into a manhole as he was running through Bedford Falls to reunite with his family.

For some films, their entire structure is built around the ending,...