Ana is a brilliant, headstrong, and compassionate mayor of a small city, with a lovely husband, daughter, and granddaughter. Yet there has been a lingering piece of her life missing - a thread of happiness she hasn't been able to pull on for most of her life. Zeno, a lifelong bachelor, bookstore owner, intrepid traveler, and theoretical physicist determined to figure out how to turn back time. Handsome, clever, and kind, he is often questioned about his failure to 'settle down.' Over the years, they have woven together an impossible and inexhaustible love. Their paths constantly intertwining, from a chance meeting on a boat to clumsily bumping into each other in the city they share. Eventually keeping in touch by letters and late-night phone calls across the world.