From the publisher website:
A century ago the fury of the storm took human form and became the Stormrider, a dark creature of boundless rage. Then, some twenty-three years ago, this great evil was vanquished and mortal men became heroes. Now the tempest rises again. The Storm Steed's hoofprints scorch the earth as the Stormrider lays waste to everything in his path. Everyone prayed that the Stormrider was gone forever ...
... but nothing lasts forever.
This Jump Start Kit is designed to introduce new players and storyguides to Ars Magica and start them playing with a minimum of preparation. This book includes pregenerated characters complete with detailed backgrounds and goals. It contains informative handouts to instruct first time players on how to read their character sheets, roll dice, cast spells, and wage combat. Finally, the story integrates elements of the original Stormrider Jump-Start Kit with new events, making it equally enjoyable for first time players and veterans of the original Stormrider scenario.