The Grim Grotto

The eleventh book in the A Series of Unfortunate Events series.
 
Violet, Klaus, and Sunny Baudelaire are intelligent children. They are charming, and resourceful, and have pleasant facial features. Unfortunately, they are exceptionally unlucky.

In The Grim Grotto, the siblings face mushrooms, a desperate search for something lost, a mechanical monster, a distressing message from a lost friend, and tap dancing...