"Demon" is an episode of Star Trek: Voyager

Star Trek: Voyager

Star Trek: Voyager is a science fiction television series set in the Star Trek universe. Set in the 24th century from the year 2371 through 2378, the series follows the adventures of the Starfleet vessel USS Voyager, which becomes stranded in the Delta Quadrant 70,000 light-years from Earth while...

, the 24th episode of the fourth season. The episode has an average rating of 3.2/5 on the official Star Trek

Star Trek

Star Trek is an American science fiction entertainment franchise created by Gene Roddenberry. The core of Star Trek is its six television series: The Original Series, The Animated Series, The Next Generation, Deep Space Nine, Voyager, and Enterprise...

website (as of May 23, 2007).http://www.startrek.com/startrek/view/series/VOY/episode/100165.html

Plot

Tom Paris

Tom Paris

Thomas Eugene "Tom" Paris, played by Robert Duncan McNeill, is a character in the television series Star Trek: Voyager. Paris serves as the chief helmsman and an auxiliary medic aboard the USS Voyager...

 and Harry Kim

Harry Kim (Star Trek)

Ensign Harry S. L. Kim, played by Garrett Wang, is a character in the television series Star Trek: Voyager. He serves as the USS Voyagers operations officer.-Depiction:...

 take a shuttlecraft down to an extremely inhospitable planet to obtain fuel. In the course of this mission exact duplicates of the crew are created by a substance found on the planet's surface. Then, after the duplicates are beamed aboard, they suffocate because they aren't breathing the planet's gases, and The Doctor is called in. After examination, The Doctor (unaware that they are clones) tells the duplicates that "the planet has adapted you," in a process the exact opposite of terraforming

Terraforming

Terraforming of a planet, moon, or other body is the hypothetical process of deliberately modifying its atmosphere, temperature, surface topography or ecology to be similar to those of Earth, in order to make it habitable by terrestrial organisms.The term is sometimes used more generally as a...

. After a study, Torres

B'Elanna Torres

B'Elanna Torres is a main character in Star Trek: Voyager played by Roxann Dawson. She is portrayed as a half-human half-Klingon born in 2349 on the Federation colony Kessik IV. Torres joined the Maquis in 2370 and was serving on the Val Jean when brought to the Delta Quadrant...

 discovers the reason behind the duplicates - when the substance covers her finger, she brings it back to the table, forming an exact duplicate of her finger. Then, Chakotay

Chakotay

Chakotay , played by Robert Beltran, is a character in Star Trek: Voyager. He is the First Officer of the USS Voyager.-Character biography:...

, Seven

Seven of Nine

Seven of Nine is a fictional character on Star Trek: Voyager, portrayed by actress Jeri Ryan. Born human, she was assimilated by the Borg at the age of six. Eighteen years later, Voyager left Borg space with Seven on board, after attempts to negotiate passage through Borg space proved only...

, and the Kim duplicate beam to the planet's surface (with Chakotay and Seven in suits) and find the real Paris and Kim. Chakotay requests all five beam up, but the Kim duplicate runs away. It eventually gets beamed up. By this point, Voyager is sinking into a pool of "silver blood". Janeway finds out that the Kim duplicate "wants a family", that is, copy the entire crew into a population for the planet. Janeway agrees, under the condition of releasing Voyager. It is released, and the "silver blood" copies everyone on the ship as the planet's population.