Act I is a self-contained opening arc that establishes Thornwell, introduces the orc and goblin threat, and ends with the first hints of a greater villain. The central villain of this act is Sister Nera Vex, a low-level cultist of the Ashen Eye. She is not a monster; use her forthcoming character sheet for her statistics, spells, and tactics. The orcs and goblins are SRD monsters driven into aggression by Nera's rituals and promises.
The adventure is designed to take characters from level 1 to level 3. The party begins by defending Thornwell, then tracks the raiders through the Skarn Hills to the abandoned Skarn Mine. Inside, they face goblins, orcs, and an ogre before descending into the Ashen Shrine. There they confront Nera, disrupt her ritual, and recover the Ember Sigil. The sigil and a letter fragment point to a distant master called the Hollow Star.
This act should feel like a complete rescue-and-revenge story while planting seeds for later acts. Keep Nera dangerous but not overwhelming: she is a local agent, not the campaign's ultimate enemy. Her defeat should feel earned and should leave the party with more questions than answers.