Ronnie and his aunt are tending the Tern Rock lighthouse for two December weeks while its keeper takes a much-needed vacation. Ronnie learns to love the slap of the waves against the Rock, sleeping in a bunk, climbing the winding staircase, and lighting the great lamp each night, and he looks forward to telling his family about it at Christmas. But the days go by, and the lighthouse keeper doesn’t return to take them home . . .