Marta found the sound before she saw the problem: a low, stubborn gurgle that lived in the sink and had lately become part of the apartment’s soundtrack. It started small—an odd slurp while brushing her teeth, a reluctant drip when she washed her face—but then the water slowed into a frustrating, mocking pool. She propped a stack of mail on the counter and sighed. Between work, a freelance deadline, and a houseplant that had decided wilt was fashionable, she did not need an obstinate sink.