In the midst of a wintry season in Dewstow, Margery is excitedly preparing for her first Christmas as the kitchen manager at Summerview school. Her supportive wife, Clementine, stands by her side, encouraging her to focus on her responsibilities.

While Margery and Clementine aim to steer clear of the Christmas concert planning, which has consumed the rest of the staff, fate intervenes. During the first practice, tragedy strikes as the stage lights collapse, resulting in the death of Mrs. Large, the music teacher.

The situation takes a puzzling turn when Mrs. Smith, the Head of Drama, becomes the prime suspect and seeks help from the Dinner Lady Detectives (Margery and Clementine) to clear her name. She firmly believes that her rival, Mrs. Blossom, the drama teacher at Ittonvale Secondary, is behind the sabotage. However, there are also indications pointing to Mrs. Smith’s potential involvement.

As they grapple with this dilemma, Margery and Clementine face a difficult decision – can they trust their friend, Mrs. Smith? Moreover, as tensions rise in the kitchen, they must act swiftly to ensure their safety. Will they manage to uncover the truth and safeguard themselves before it’s too late?