"In Purgatory's Shadow" is the 112th episode of the television series Star Trek: Deep Space Nine, the 14th episode of the fifth season. The episode premiered on February 10, 1997 to a Nielsen rating of 6.7 points. It is the first half of a two-part episode, with the second half, "By Inferno's Light", first airing a week later. Set in the 24th century, the series follows the adventures of the crew of the space station Deep Space Nine near the planet Bajor, as the Bajorans recover from a decades-long occupation by the imperialistic Cardassians. The station is adjacent to a wormhole connecting the Alpha and Gamma Quadrants of the galaxy; the Gamma Quadrant is home to an expansionist empire known as the Dominion, ruled by the shape-shifting Changelings. This episode begins the Dominion's invasion of the Alpha Quadrant, a plot arc which continues until the final episode of the series. It features the return of several characters, drawing on plot lines previously established in the third, fourth and fifth seasons. This episode is dedicated "In memory of Derek Garth", a grip for the series who died in an automobile accident in December, eight weeks before the episode aired. Plot When Deep Space Nine picks up a mysterious coded message from inside the Gamma Quadrant that appears to be Cardassian, exiled Cardassian spy Garak is asked to analyze it. He told everyone that the message was a harmless report from years ago, but Dr. Bashir sees through his lie when Garak tried to sneak away on a ship. He reveals that the message is a distress call from his mentor Enabran Tain, who was believed to have been killed in an ill-fated Cardassian attack on the Dominion two years prior. Garak convinces Captain Sisko to allow him to travel to the Gamma Quadrant, accompanied by Lt. Cmdr. Worf, to search for Tain and other possible survivors from Dominion attacks. Soon after entering Dominion space, they wind up in the midst of the Dominion fleet. Worf realizes that the fleet must be assembled to invade the Alpha Quadrant. He sends a warning message to DS9 just before Jem'Hadar soldiers take him and Garak prisoner. Back on DS9, the crew receives Worf's message and realize the Dominion is coming. With reinforcements at least two days away and only disgraced Cardassian officer Dukat (on the station due to a confrontation with a Klingon battle