Back to the past. At a time when the entire Earth was covered with ice and all living things were dying from the cold. Flocks of surviving animals fled south in search of safety, food and warmth. In such a harsh time, a sloth named Sid, a mammoth Manny and a saber-toothed tiger Diego met. But in addition to the usual difficulties that awaited friends along the way, they were also awaited by an involuntary "fatherhood" for a human baby.