To Storm Heaven (Star Trek, the Next Generation)

When Lelys, ambassador of the plague-ridden colony planet of Orakisa, approaches the Federation seeking help for her dying world, the U.S.S. Enterprise speeds to the rescue. Captain Picard and his crew escort the Orakisan delegation to its long-lost sister-world, Ne'elat, where the ambassador and the Away Team are initially welcomed, but then endangered. As the Enterprise officers make their way through a web of planet-wide intrigue, time is running out the people of Orakisa and the inhabitants of their sister-worlds as well.