The Restless Spirit is a song that makes its debut in the eighth Dark Parables game, The Little Mermaid and the Purple Tide.
In-Game Appearance Edit
The Little Mermaid and the Purple Tide Edit
In this game, it is used as background music for puzzles and FROG scenes. Interestingly, when the song is downloaded, two files are downloaded and one is titled "Into the Breach" and the other is "The Restless Spirit". It's possible that the developers forgot to include a download for this song, or maybe it wasn't meant to be added. The title is a reference to the Goddess, Thalassa.
To download the songs for yourself, go to the Bonus Content in The Little Mermaid and the Purple Tide and select the "download" option next to the song. To listen, simply click the play buttons in the info-box above.