A Federation planet whose population was threatened in 2364 by an outbreak of Anchilles fever, sending the Enterprise-D to Ligon II in search of a vaccine.
Styris IV is an inhabited Federation planet referred to in the first-season Next Generation episode Code of Honor. It is not shown on screen.
In 2364 the planet suffers an outbreak of Anchilles fever, a fast-spreading disease expected to cause deaths in the millions. The only effective vaccine cannot be replicated and is found on Ligon II, so the Enterprise-D is sent to negotiate with the Ligonian leader Lutan for a supply.
The urgency of the crisis on Styris IV shapes Picard's decisions throughout the episode. When Lutan abducts Tasha Yar and later demands that she fight a duel to the death, Picard feels unable simply to take her back by force, because doing so could cost the vaccine and with it the lives of the planet's people.