In a castle, one stormy evening, Doctor Carter and a whole merry company find themselves welcomed by the four brothers who hold the place. The four obese disappear one by one, without leaving a trace.
Taking advantage of their uncle's absence, André and Raymond Rafet organize a New Year's Eve party at his house. The uncle returns unexpectedly, disturbs the party, threatens his nephews to disinherit them and then locks himself in his office. A few minutes later, he is found dead, poisoned.
