Anna Gallagher & Liam Harrison are happily married have successful careers & when Liam's promotion comes through they plan to start a family. That's until something happens to turn their world upside down. Anna's sister Rachel is married to Gary is a stay-at-home mum to Alex & is expecting her second child. Everyone is delighted with the news except Rachel. The truth is she is horrified at the thought of becoming a mum again. Jill is the girls' cousin & best friend & knows exactly what makes them both tick. Unfortunately she can't seem to help them understand each other. The Gallagher Girls have hard times ahead but when the going gets tough will blood really prove thicker than water?