“In the world of the new movie Fingernails, any two people who believe they have fallen in love can take a test to prove it. It’s simple enough: Each partner must rip out a fingernail, wait a few minutes for a microwavelike contraption to inspect it, and voilà! A result. A 100 percent score means a perfect match—and peace of mind. Fifty percent indicates that only one person is in love. And zero? Well, you know.”