The faculty of Willow Creek High School are having a get-together after the spring concert with refreshments provided, courtesy of Daisy's Tea Garden. Oolong tea and chocolate biscuits are just what the staff needs to help them unwind from Althea Higgins' demanding curriculum. Her lessons on such controversial subjects as school uniforms and under qualified substitute teachers are earning her an F from her colleagues. But a failing grade was preferable to Althea falling victim to foul play. Daisy was there when her body was discovered in the school swimming pool, murdered by strangulation. Althea was certainly a strict, opinionated taskmaster, unliked by both teachers and students, but would any of them actually want to kill her? As Daisy starts asking questions, she gets a real education in Althea's history, discovering more than enough enemies with more than enough motives to cancel her classes permanently...