Sam likes being a twin. He likes having two mums. He likes cheese sandwiches and his dog and drawing comics with his friend Pea. He does not like humus - or heights. His twin sister Sammie likes being a twin too. She knows that she's perfect best friend material for somebody - the girls in her class just haven't realised yet. And she knows that she's the best Sam - Sam A. Both Sam and Sammie - and everybody in their lives seems to be keeping secrets - which ones will come out?