Shadowing an Excise officer in a tobacco factory, Nick Storey finds he is using incorrect procedures. When Nick carries out the right ones, he discovers that the company are importing large amounts of tobacco illicitly. But the evidence goes missing and Nick starts to feel the hand of Freemasonry protecting the firm and encouraging him to let matters drop. However, some unofficial surveillance and Rosemary going undercover leads to where the smuggled tobacco is being concealed. Seizing it has tragic consequences for those Customs officers involved and it requires a desperate evening's work to resolve the situation. "Magic Clarinet" is the fourteenth book in a series of detective stores set in HM Customs & Excise, by Richard Hernaman Allen, a former Commissioner.