My Lucky Charms (2004)

From Introduction:

Everyone knows about Leprechauns. You see them in cartoons, grinning from cereal boxes and frolicking on the silver screen as fun-loving, mischievous little men in green hats. It is the legend of their gold that we all know best, though. Leprechauns were tasked with guarding the gold and treasure of the fae, hence the “pot of gold” legend. The gold could always be found at the end of a rainbow so the poor Leprechauns would forever have to move the gold to prevent its discovery by humans. Some tales say that Leprechauns sometimes reveal the location of their gold to humans when they have had too much to drink.

The truth is no where near that pretty. Leprechauns are real and human lives are their “treasure”. Pinebox is home to one and his name is Mickey. He is a serial killer that preys on young women once a year, during the days surrounding St. Patrick’s Day. No one has ever stopped him because no one even knew he existed… until now. The ghost of a previous victim now seeks to make the PCs aware of Mickey so that they might put an end to the killings. Will they succeed or simply die at the end of the rainbow?