The GSG Videogame Storyline

In the discussion about whether the Gunslinger Girl videogame trilogy could be considered canon or not, one of the things that I was left wondering about is what exactly happens in the games. While I know that it introduces a new fratello - Ernest/Pia - and that Ernest revolts against the Agency and drags his loyal cyborg into the rebellion, there's really little else on the web - hell, entering "pia gunslinger girl" on a Google image search brings up the Welcome to Pia Carrot H-games before there's a hint of a GSG videogame screenshot!

Is there a synopsis of the games' plot available, the personalities of Ernest and Pia and any other significant characters in the games, or is it simply nothing more than "fratello rebels, recapture them, kill any Padanians in the way?"

Review - http://www.gamesetwatch.com/2006/06/column_the_gaijin_restoration_12.php

Walkthrough of Volume 1