It's Valentine's Day, and something curious is going on. As the birds tweet their love songs, Hippo and his friends Elephant, Pig, and Turtle each receive mysterious, unsigned Valentine's Day cards. Hippo wonders if his is from Duck; Elephant and Turtle think theirs are from Pig; and Pig dreams that hers is from Turtle. When they show up to a four o'clock party in the park to find out who their valentines are, they are totally surprised.