Daniel and Dylan are the top swimmers in the world; Alex and Ali, the top tennis players. They play for God, country, family, and the need to escape their troubled pasts. In their quest to be the best, they also harbor a secret: Each is in love with his rival. The four hit it off at the Summer Olympics in New York and reconnect on an island vacation that gives new meaning to doubles, round-robin, and preliminary heats. By then, the shifting professional fortunes of each couple have begun to signal a change in their personal relationships as well, one that will lead to new alliances and...