I've finished reading the first book in the Darth Bane trilogy

It was a really page turner, pretty thoroughly.

The protagonist, Dess gets dealt a bad hand in life but finds survival in joining the Sith military forces, eventually training to use the force within the academy.

He can see the modern Sith are weaker by abandoning the old ways and sets out to destroy them in order to rebuild it with himself as it's new head, Darth Bane