Producers: Greg Strause, Colin Strause and Liam O’Donnell   Director: Liam O’Donnell   Screenplay: Liam O’Donnell   Cast: Lindsey Morgan, Jonathan Howard, Daniel Bernhardt, Rhona Mitra, Naomi Tankel, Cha-Lee Yoon, Jeremy Fitzgerald, Iéva Andrejevaite, James Cosmo, Yayan Ruhian and Alexander Siddig   Distributor: Vertical Entertainment

Grade: C-

It would have been difficult to believe back in 2010, when “Skyline” was released, that the SyFy Channel-quality alien-invasion potboiler would spawn a franchise, but here’s a third installment, which takes up a few years after the first sequel, “Beyond Skyline” (2017) left off.  (One might have wished that writer-director Liam O’Donnell would have gone with “Beyond Beyond Skyline” as the title, but instead he’s opted for “Skylin3s,” mimicking the numerical affectation David Fincher followed with “Se7en.”)

If you haven’t kept up with the “Skyline” plot over the decade, O’Donnell provides, through the agency of a grizzled old storyteller named Grant (James Cosmo). a brief, frenzied recap up front, though it will hardly be enough to keep someone new to be franchise from being hopelessly confused.  But they will soon have company, since this new entry becomes so convoluted that it will probably puzzle even old fans of the franchise.

Grant’s tale ends with how Rose Corley (Lindsey Morgan), the human-alien hybrid, froze in the final battle with the so-called “harvesters” from another world, leading to a victory, but one in  which many needlessly died.  Understandably depressed, she’s gone off the grid, but in this continuation, penned by O’Donnell from a story he devised with Matthew E. Chausse, the authorities track her down five years later, take her into custody and assign her a new mission.

It seems that the harvesters have unleashed a virus that will cause those of their race that have stayed on earth as comrades of the humans, because of the harvested human brains they now house, to revert to their hostile ways while another invasion from their home world completes the takeover of the planet.  (At least that seems to be what’s happened.)  So General Radford (Alexander Siddig ) is assembling a team to travel to the harvesters’ home, a place dubbed Cobalt 1, to locate and steal a glowing whatsit that can reverse the virus effect. 

Rose is charged to be part of the expedition, along with her brother Trent (Jeremy Fitzgerald), who takes after the alien side of the family, physique-wise (also linguistically: he delivers his lines in grunts with subtitles).  The rest of the team is populated with stock characters chosen for various skills—soldiers and scientists named Leon (Jonathan Howard), Owens (Daniel Bernhardt), Zhi (Cha-Lee Yoon) and Alexi (Iéva Andrejevaite) who, while not indistinguishable, are mostly one-note figures, and their jokey dialogue is frequently just dumb.

After their arrival on alien terrain the group gets involved in multiple stand-offs with the enemy in their effort to acquire the thingamabob.  Martial arts-style face-offs seem to go on forever, and in the course of all the fighting, motives clash and an unsurprising twist reveals that some have a purpose in mind very different from the stated one. 

Meanwhile there’s another struggle ongoing back on earth, where Dr. Mal (Rhona MJitra) is engaged in trying to develop an antidote to the virus and, along with cohorts including Grant, contending with aliens who have reverted to their ravenous former selves.  In the final stages of the film O’Donnell jumps from one battle zone to the other, shuffling between Cobalt 1 and earth in endless variations that drag the running-time to nearly a full two hours, though extended closing credits, complete with gag outtakes that mar whatever credibility the plot might have had, take up a good deal of time.  Inevitably there’s also a nod to a prospective follow-up in terms of an allusion to Rose’s father (Frank Grillo) from the first sequel, whose reappearance would presumably drive a continuation.

Nobody in the cast particularly distinguishes him or herself, though Morgan is a capable female warrior in the mold of Kate Bekinsale’s “Underworld” Selene or Milla Jovovich’s “Resident Evil” Alice.  While Siddig chews the scenery in expected fashion, Mitra is largely wasted. But old pro Bernhardt proves he still have some moves, and Yayan Ruhian shows up for some brief action as well. 

Though the effect would doubtlessly pale on the big screen, in streaming form “Skylin3s” looks fairly impressive, with the VFX supervised by Thomas Loeder and the Creature SFX overseen by Fito Dellibarda better than the modest budget might suggest.  The production design (Cédric Van Eesbreek) and cinematography (Alain Duplantier) are less impressive, and Barrett Heathcote’s editing sometimes lags, but Ram Khatabakhsh’s bombastic score certainly tries to keep things pumped up.

“Skylin3s” is a highly derivative, confusing, often risible hodgepodge, made up of bits and pieces from other, better sci-fi movies, and at best a mediocre contribution to the genre; but its two predecessors inexplicably created a fan base that justified it being made, so perhaps there’s a built-in audience for it.