Kai and Zoe aren't just sisters; they are best friends. Wherever Kai goes, Zoe follows. Whatever Kai does, Zoe does too. In sickness and in health, Zoe is there for her big sister. But their relationship is soon tested when there is only room for one in a treehouse. Will Zoe like her newfound freedom? And will their relationship ever be the same? Poignant and humorous, Kai & Zoe shows the true meaning of sisterly love.