Every day Mr. Grinling rows from his cottage on the cliff out to the lighthouse, where he works all day. His wife prepares him delicious lunches, which she sends to him via a pulley system between the cottage and the lighthouse. Problems begin when hungry seagulls steal Mr. Grinling’s lunch as it travels over the sea. Its is decided that Hamish, the Grinlings’ cat, will accompany the lunch, but he becomes seasick and the seagulls, unthreatened by him, still have a feast. But they are finally defeated when Mrs. Grinling puts mustard into her husband’s sandwiches!