Manny and Sid journey on, Manny bothered by the sloth’s constant talking, until the two find Nadia on a riverbank, weakened greatly by her jump over the falls, with hardly enough strength to pass her son to Manny before she disappears. Manny leaves, but Sid intends to return the baby to his “herd”, which Manny will not help with. The two meet Diego, who takes the baby, claiming that he intends to return him to the humans. Manny, unconvinced, decides to help Sid return the baby to his family, leaving the saber behind; the humans’ camp is abandoned and Manny reluctantly decides to head north to find the humans’ settlement at Glacier Pass and return the baby, taking Diego along as a guide.
The trio take the baby up north and meet a fanatical flock of dodos on the way, from which they procure food for the baby. During the trek, however, Diego secretly meets up with two of his pack mates, who pass a message from Soto, demanding the baby; Diego sends them back with a message to Soto, promising the baby and Manny. The following morning, Sid takes the baby to a mud crater, where he meets two female sloths named Jennifer and Rachel, who he tries to court using the baby, which Manny takes back; Sid returns to the mud crater, only to find the sloths gone, Carl and Frank in their place. The rhinos pursue Sid, who runs into Diego and pleads to the saber to deter the rhinos: Diego pretends to have killed Sid to throw the rhinos off the trail and releases his grip once the rhinos leave; Diego then moves on with Manny and Sid. On the way, the group runs into a number of predicaments, from a changing landscape to freezing ice age blizzards. The group meets Scrat, who had seen a pack of sabers go by and tries to tell Manny before Diego surreptitiously flicks Scrat away.