The family struggles as Rosie hits puberty. She becomes erratic before, out of the blue, her genetic condition is diagnosed, and Si and Em come to terms with why Rosie is Rosie.

Rosie's excited as they set off for the annual summer holiday but things are not as she was expecting. In 2009 Si and Em are confronted with Fliss, their perfect new niece.

After the school notices some bruising on Rosie, Si becomes paranoid about a visit from social services. In 2008 Rosie takes her first steps leading to unforeseen new problems.

As Em gets excited about Si's annual quiz, Rosie becomes fixated on making her draw a specific picture over and over again. In 2008, Rosie suffers a frightening medical emergency.

Rosie becomes obsessional about Christmas, unable to understand why it can't be Christmas all the time. In 2007, Si and Em continue to drift apart and consider splitting up.

Rosie starts to say 'mama', raising hopes that her communication will finally take off. Emily feels totally outshone by Rosie's amazing schoolteacher and concentrates on developing her daughter's sign-language, while Simon worries that the other parents of special needs children look down on him. Things come to a head at the school sports day.