The secret of the "old towers". Bliton E.

The famous five goes to the snowy Welsh mountains. The guys are not tolerated to ride a sleigh and skiing. They have a great time, but once in the window of a mysterious house they notice an old woman who gives them some signs. Friends suspect that she is kept in the "old towers" locked up, and decide to find out if this is so. What if the imprisonment of the prisoner is somehow connected with the prey of rare ore in the mountains?