The film stars Michael Madsen, Natasha Henstridge, Marg Helgenberger, Mykelti Williamson, George Dzundza, James Cromwell and Justin Lazard.

The plot has Patrick Ross, the astronaut son of a senator, being infected by an extraterrestrial organism during a mission to Mars and causing the deaths of many women upon his return.

While participating in a human mission to Mars, astronauts led by Commander Patrick Ross, Anne Sampas, and Dennis Gamble collect soil samples.

While returning to Earth, the soil thaws and releases an alien substance that contaminates them and causes a brief contact gap with mission control.

To his horror, the pair undergo accelerated pregnancies and die giving birth to human/alien hybrids, which he hides in his father's remote shed.

Meanwhile, under military supervision, scientists led by Dr. Laura Baker have created a more docile clone of Sil named Eve in an effort to understand the alien life form and prepare for defense should it ever arrive on Earth.

That night, Ross commands his offspring to form a cocoon so they can reach their adult stages and repeat the cycle on a global scale.

While the military arrive to escort the team away, Eve is loaded into an ambulance, where she is joined by Ross's remaining offspring while her womb rapidly swells, the screen the goes black, leading to the events of the third film.

Writer Chris Brancato was working with MGM on The Outer Limits, and knew the studio was interested in making a follow-up to Species.

Foster liked it, but once Brancato went to Species producer Frank Mancuso Jr., he asked to "approach this from a different angle, so that we don't have a tired retread of the original, as sequels often are".

Mancuso approved the idea, and thus Brancato explored how this new villain was one "for whom we can briefly feel a strange, Wolf Man-like sympathy – he's not responsible for having been turned into a monster" and had him face an alien woman similar to Sil, raising the doubt on whether they would battle or mate.

[3] Brancato decided to bring back two of the surviving characters from Species, Michael Madsen's Press Lennox and Marg Helgenberger's Dr. Laura Baker feeling they "were essential to bring the audience back in", but knowing Forest Whitaker was probably too busy to return as Dan Smithson, he wrote a similar African American character in the one eventually portrayed by Mykelti Williamson.

[2] Mancuso had another script done simultaneously to Brancato's, which reportedly explored the cliffhanger ending of Species where a rat was infected after eating Sil's remains.

It is also stipulated that they were a "cancerous" race that visited Mars millions of years ago and annihilated all life on its surface (which is described in the film as being Earth-like at that time) before leaving a remnant of their own DNA in its soil.

The site's critical consensus reads: "Clumsily exploitative and sloppily assembled, Species II fails to clear the rather low bar set by its less-than-stellar predecessor".

[14] James Berardinelli described the film as awful but added "there's enough blood, gore, simulated sex, and bare flesh to prevent it from ever becoming boring".

Other details in the book that do not appear in the film include an earlier escape attempt by Eve, and Patrick discovering new senses in a restaurant with his fiancé.