Arsenic for tea

Schoolgirl detectives Daisy Wells and Hazel Wong are at Daisy's home, Fallingford, for the holidays. Daisy's glamorous mother is throwing a tea party for Daisy's birthday, and the whole family is invited. But it soon becomes clear that this party isn't really about Daisy at all. Then one of their party falls seriously, mysteriously ill and everything points to poison.