Scrat, trying to bury his acorn, accidentally activates an abandoned alien ship that takes him into deep space, where he unwittingly sends several asteroids en route to a collision with Earth. Meanwhile, Manny is worried about the upcoming marriage between Peaches and her fiancé, Julian. Diego and his wife Shira want to start a family, but their fierce appearance tend to scare kids. Sid is dumped by his girlfriend, Francine, just as he is about to propose to her, and he laments his solitude. During Manny and Ellie’s wedding anniversary party, some of the asteroids strike the place and the herd barely escape with their lives. Meanwhile, at the underground cavern, Buck returns a dinosaur egg back to its rightful owner after it was stolen by a trio of dromaeosaurs named Gavin, Gertie, and Roger. Buck discovers an ancient stone pillar and takes it to the surface, where he meets Manny and the others.