DS9 Season 4 DVD
Star Trek: Deep Space Nine – The Complete Season Four is a DVD release containing all of the episodes which were broadcast during the series' fourth season.

Summary 
From the DVD booklet:

Welcome to the fourth year of the adventures of Deep Space Nine, remote and abandoned Cardassian outpost stationed on the very edge of the known universe.

This is the year in which the Klingon Empire joins the struggle against the Dominion in force.

Beset by paranoid Klingon forces led by the ferocious General Martok, Sisko calls for the one man who can deal with the unpredictable ally: Starfleet's first Klingon officer – Lt. Commander Worf.

While the hunt for Changeling infiltrators continues on Cardassia, Qo'noS and Earth, the crew of Deep Space 9 deal with additional complications. Sisko fights a plot to overthrow the leadership of the United Federation of Planets. Dax faces expulsion from the Trill Homeworld and the enforced death of her symbiont.

Kira joins forces with the hated Gul Dukat not once, but twice. Odo must accept Kira's relationship with a powerful Bajoran politician. O'Brien lives through 20 years of hard labor in an alien prison.

After a visit to Roswell, Earth, in 1947, Quark is forced to sell his remains on the Futures Market, despite still being alive. And Julian Bashir lives out his fantasy as a 1960s secret agent.

While Deep Space 9's officers soldier on, the Klingons, the Cardassians, the Maquis and the Jem'Hadar seem determined to bring the battle to Starfleet.

Welcome to 2372. It's going to be a long and eventful year...

Episodes

Special Features 
Charting New Territory: Deep Space Nine Season Four – A general season overview where cast and crew discuss developments such as Worf's integration into the series, amongst other topics.

Crew Dossier: Worf – Features interviews with Michael Dorn on the subject of his Klingon character, Worf.

Michael Westmore's Aliens, Season Four – Michael Westmore presents an insight into the process of designing aliens for DS9's Fourth Season.

Deep Space Nine sketchbook: John Eaves

Robert Blackman's Designs of the Future (Region 2 only)

Jim Martin Sketchbook (Region 2 only)

Deep Space Nine Chronicles (Region 2 only) – The cast introduce selected episodes of DS9's first four seasons.
Photo Gallery

Section 31 – Hidden files (otherwise known as Easter eggs, when present on DVDs).
Hidden File 01: Alexander Siddig (Julian Bashir) explaining his love and admiration of the episode 
Hidden File 02: Armin Shimerman (Quark) interview (regarding ) 
Hidden File 03: Nana Visitor on playing Russian agent Anastasia Komananov in 
Hidden File 04: Susanna Thompson (Lenara Kahn) interview (about working on )
Hidden File 05: David Livingston (Director) on directing 
Hidden File 06: Gary Hutzel (Visual Effects Coordinator) on filming masses of Klingon starship models for 
Hidden File 07: Ronald D. Moore (Writer) interview (regarding )
Hidden File 08: Chase Masterson on playing the role of Leeta
Hidden File 09: Michael Dorn (Worf) interview (regarding )
Hidden File 10: Robert O'Reilly on playing the role of Gowron

The special features that were lacking on the regular Region 1 releases, were for that region only available as a "retailer exclusive" on a separate disc through the Best Buy retail chain store.

Background information 
The region 1 artwork on the discs features a Klingon Bird-of-Prey flying from the wormhole by the station.

The region 2 artwork on the discs features various characters from the season:
Disc one – Jaresh-Inyo
Disc two – Dukat
Disc three – Kurn
Disc four – Akorem Laan
Disc five – Jennifer Sisko (mirror)
Disc six – Onaya
Disc seven – Trevean

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sr:ДС9: Сезона 4 (ДВД)