Mr. Grinling, the lighthouse keeper, lives in a cottage perched on a cliff with his wife, Mrs. Grinling. Every day, Mrs. Grinling prepares a delicious lunch and sends it to him via a special cable system. However, the seagulls have discovered this tasty delivery method and begin stealing his lunch. The Grinlings must devise a clever plan to outwit the greedy birds and ensure Mr. Grinling gets his meal.