When a radical experiment into the nature of time is sabotaged, the scientific team finds themselves in an alternate universe, where humans never became the dominant life force. Instead, dinosaurs evolved into intelligent bipeds, developing language and societal structures.
The scientists have to learn to communicate with this alien species, who view them as unusual pets, and figure out how to recreate the original experiment in a non-industrialized world, so they can go back home—assuming there's a home, or even a universe, to return to.
But the scientist who sabotaged them is trapped in this new world with them. And he's looking to rise to power, even if his quest means the death of his traveling companions.