Maggie Eliot is learning the truth of the adage, "No good deed goes unpunished." To help a friend, she has agreed to host a group of American botanists who are touring the Cotswolds during snowdrop season. If only it were not for the relentless rain, which has left much of southern England under water and forced Maggie's visitors to extend their stay for several days. With her husband Thomas grumpy about having to undertake some unwelcome estate planning, Maggie can expect no support when one guest breaks her ankle and another is caught snowdrop poaching. Then one of the party dies suddenly and makes Maggie's other problems seem trivial. It looks like it was a heart attack, but the police insist on an autopsy to confirm the cause of death. When another guest dies suspiciously, Maggie is forced to entertain a house party that may include a double murderer.