The Carles' household is home to one of Britain's most extraordinary families: Meet Ellie, Georgie, Jessica and Holly - the UK's only identical quadruplets. We follow these miracle girls in the run up to their fifth birthday, sharing with them some of the milestones of their lives from Christmas to their first day of term. On the way, we'll explore how the girls are growing up and changing, and using psychological testing will examine how different the quads really are. This is an intimate portrait of an extraordinary family that answers the big question - what's it really like to be Four of a Kind?