Things That Go Boom

From the introduction:

A goblin alchemist has developed primitive grenades and uses them to attack caravans and gain followers. It falls to the heroes to confront this menace and break up his small but growing band before it grows into a force too powerful to reckon with. Things That Go Boom is a single EL 4 encounter/adventure for characters level 1 -4. As a DM you can drop it into nearly any campaign or run it as a one-shot.