The Canadian indie thriller “Son of Sara” is the goriest “Rosemary’s Baby” homages to come along in years.

Childbirth at its most bloody, a graphic throat-slitting opening scene determined to make us watch somebody bleed out in real-time, a Lin Shaye look-alike as a villain and full frontal nudity are part of the package. But maybe the cheekiest thing about writer-director Houston Bone’s follow-up to “I Don’t Know Who You Are” might be its full title — “Son of Sara: Volume 1.”

Really? OK then. It’s not like he’s painted himself into a corner with this plot. And why should Hollywood be the only place where every horror tale is treated as “franchise” material?

“Sara” is a thriller that promises zero surprises right from the start, and then half-dashes its way to an utterly pre-ordained ending.

A prologue features a screaming, chained young pregnant woman pleading “Don’t take my baby!” before she gurgles her last. Some entity with bright red eyes that glow in the dark is involved, we’re sure. And sure enough…

“Three Weeks Later” we meet Sara (Chloe Van Landschoo of TV’s “From”), very pregnant and very much in love with bartender Carol (Tymika Tafari of TV’s “Slip”). Maybe a little sex will induce our overdue mom-to-be. A song by Cigarettes After Sex — you know the one — sets the mood.

The baby daddy? “Troy” isn’t in the picture. A chance meeting on the street reveals why he never called. But hey, she’s pregnant. Maybe she’d like to visit him (Garrett Hnatiuk) on his mom’s farm? As we all know that “babies are expensive,” Sara accepts the invitation with the possibility of child support, over Carol’s furious objections.

Troy’s evasions about giving Sara the address as he drives her there are a “tell.” Meeting Troy’s mom (Jane Moffat) is another. The lady could be horror icon Lin Shaye’s kid sister.

A tour of the thirty acre spread is in order. Troy’s in charge of the farm’s operation, and seeing an old barn, Sara asks “It this where the magic happens?” His answer should give her pause

“You could say that.”

As we’ve seen Sara’s appetite for raw meat — the bloodier the better — we can hardly wait for dinner, much less the weary, bleary calls to Carol’s voice mail pleading for her to join them. We’ve leapt to the ritual and on to the finale long before things go over the top.

That bloody birth foreshadowing prologue has less to do with the narrative than you’d expect. And its “spoiler alert” inclusion robs the picture of any mystery at all. Lacking that, all we have to cling to is the suspense, and even that’s slack and lacking.

The acting isn’t bad, as such messes go. And to be fair, “Rosemary’s Baby” was a LONG time ago, even if “Devil’s Due,” “Blessed” and “Deliver Us” aren’t. Maybe some potential viewers won’t know the worn out tropes of such films.

Still, there are audience participation options here. Every bloody vomit and kiss the messy vomiter bit of business could prompt a collective “Ewwwwwww.”

But “Volume 1” seems most ambitious in its titling. I guess the surprises are all saved for the sequel?

Rating: unrated, graphic, gory violence, full frontal nudity, sex, profanity

Cast: Chloe Van Landschoot, Tymika Tafari, Garrett Hnatiuk and Jane Moffat.

Credits: Scripted and directed by Houston Bone. A Saban release.

Running time: 1:28