The protagonist (you) of this story Tilia (soon to be 20) is a little bit of a tomboy.
One day, when she was working, a mysterious man appears before her.
He abducts and takes her to a man named Sirius.
This man Sirius, tells her that a secret lies behind the death of her parents and that if she wanted to know that secret then she would have to do some investigation work on his behalf at the Bilballard palace...

In order to find out the secret, Tilia ends up working as a servant at the palace.
But will she really be able discover the truth behind her parent's unexplained death?

[From DLsite English]