In the opening episode a chilling possibility is proposed as to why might be: have the Changelings infiltrated already and replaced key personnel? Some fans saw this as a flawed X-Files-style development. Nevertheless it sowed a seed of insidious suspicion from here on, affecting all the principal casts' relationship with one another, even allowing Odo and Quark an opportunity to confess a degree of friendship. Expanding on the new theme of duplication, the crew also made numerous trips to their Mirror Universe counterparts.

As well as new uniforms and the milestone 100th episode, Nana Visitor and Alexander Siddig comically got to disguise the arrival of their child during filming. More laughs came from the fan favourite "Trials and Tribble-ations" with CG allowing Sisko and crew to interact with Kirk and a cameo from Leonard Nimoy. Avery Brooks began taking a backseat as of this year, partly a result of the now-overcrowded cast. Although Sisko's destiny would be foreshadowed by his first vision and the introduction of the Pah-wraiths, the Captain was in an increasingly sulky mood. Brooks only directed one episode, allowing room for regulars LeVar Burton and Rene Auberjonois to do more behind the camera. Joining them were Alexander Siddig, Michael Dorn and even Andrew Robinson. Available space started to seem hardly deep enough. --Paul Tonks

Synopsis
The third Star Trek series concerns Benjamin Sisko (Avery Brooks), commander of the starship Deep Space Nine, who discovers the first known stable wormhole--a virtual shortcut through space that leads from the Alpha Quadrant to the Gamma Quadrant on the other side of the galaxy. The Gamma Quadrant is governed by the Dominion, a group led by the Changelings--a race of shapeshifters which counts DS9 crew member Odo (Rene Auberjonois) among its numbers. The Dominion has become a violent force in the galaxy, and the Deep Space Nine and its crew has become the only hope in upholding the way of life established by the Federation. This 7-disc set includes all 26 episodes from the fifth season.
Comprises the episodes:
99 Apocalypse Rising
100 The Ship
101 Looking for par'March in All the Wrong Places
102 ...Nor the Battle to the Strong
103 Trials and Tribble-ations
104 The Assignment
105 Let He Who Is Without Sin
106 Things Past
107 The Ascent
108 Rapture
109 The Darkness and the Light
110 The Begotten
111 For the Uniform
112 In Purgatory's Shadow
113 By Inferno's Light
114 Doctor Bashir, I Presume