John Sheppard and Rodney McKay must chaperone an upstart young princess and avoid a squadron of hostile Genii in a brand new episode of Stargate Atlantis. GateWorld has received new story details on Season Four’s fourteenth episode, “Harmony,” which will make its world premiere this Friday at 10 p.m. (Eastern/Pacific) on SCI FI Channel.

The episode guest stars young actress Jodelle Ferland as the 13-year-old title character. Ferland played the child Adria in the Stargate SG-1 episode “Flesh and Blood,” and has been featured in such films “Silent Hill.”

Here’s how SCI FI describes this week’s episode:

While re-visiting an off-world trading partner, Lt. Colonel Sheppard and Dr. McKay receive high praise from the beautiful princesses Mardola and Flora who express their undying gratitude for the trade, medical assistance and protection Atlantis has provided for the past several years.

The princesses beg a further favor, asking Sheppard and McKay to accompany their sister Harmony, designated successor to the throne, to the ruins of the Temple of Laros, a mandatory rite of passage. Reluctant to jeopardize their otherwise untroubled alliance and anticipating that the third sister will be equally beguiling, Sheppard and McKay agree to escort Harmony on a journey promised to take no longer than a day.

Their chivalry is challenged upon meeting Harmony, a thirteen year old child with high expectations of her protectors. Disheartened, Sheppard and McKay nonetheless proceed with their mission, unaware that she has enemies, and character flaws, yet to be dealt with.

Watch a preview scene from the episode now at GateWorld Play!

“Harmony” premieres Friday at 10 p.m. Eastern/Pacific on SCI FI, and Tuesday, January 29 on Sky One in the United Kingdom.

MGM has posted photos and a video teaser from the episode at their official Stargate Web site.

Learn more about “Harmony” and other upcoming episodes in GateWorld’s Season Four episode guide!