This is an automatically translated description

From the publisher:

Princess Philomena cannot leave the walls of her father's castle until she turns eleven years, eleven months, and eleven days old. But her desire to break free is so irresistible that the girl breaks the laws of Ancient Magic and... finds herself in the Serpentine Mountains, in a gloomy underground palace guarded by a Serpent. Now she will have to turn from a princess into a maid and perform very unusual work until... Well, you will read about it yourself.