In the year 1014, outside Dublin, the good Celtic King Brian Boru entrusts his faithful servant Endrick to guard his people's treasure trove. Endrick's pregnant wife Erin gets kidnapped by a clan of gypsy lepers, the Chauns. The vile, evil Chauns demand that Endrick betray his king by handing over the Celts' prized treasure. Endrick is torn between his loyalty to the king and his love for Erin and their unborn child.
Time travels to modern day when a wily cad named Gypsy Jones finds the only missing piece of the legendary treasure, King Boru's gold sword, at a rummage sale. Jones sets out on a mission to capture the only one who can lead him to the treasure – Endrick, who got turned into a leprechaun as punishment for his betrayal.
A fast-paced pursuit to catch the leprechaun ignites, with a motley myriad of wacky eccentrics joining Jones' quest. Endrick and his adopted son Davy try to stay one step ahead of the gang, using ingenious trickery and fascinating quick-wittedness. The tale takes us back to the Emerald Isle, where Princess Shannon awaits the treasure-hunters...