From book cover:

The purring of an engine was the first warning, and Holly sensed a shape moving in the blackness. Before she had time to react, there was a blinding blaze of light; then with a surge of power, the car came roaring towards her...

The Mystery Club visits Holly's aunt for a week's relaxation by the sea - and walks straight into a complex and dangerous mystery. What are the strange lights coming from the uninhabited island? Whoever is behind them is determined to stop The Mystery Club finding out!