"A research scientist is experimenting with human DNA in an attempt to create the perfect human being. His work has made it to the point where he can take a human fetus and accelerate its growth to that of an adult within a few days. His latest creation is a (spoiler omitted), but side effects from the process (spoiler omitted)," according to the DVD sleeve's synopsis.
"Embryo" opens by promising: "The film you are about to see is not all science fiction. It is based upon medical technology which currently exists for fetal growth outside the womb. It could be a possibility tomorrow
or today," according to Dr. Charles M. Brinkman III. Right. And, Dr. Joyce Brothers appears, later, at a party with Roddy McDowall.
First, we see Rock Hudson (as Dr. Paul Holliston) light a cigarette and drive recklessly (watch that speedometer!) during a storm; unfortunately, he hits a dog. Mr. Hudson takes the wounded canine home. He learns it is pregnant, and manages to save the life of one of the puppies, due to his experimental knowledge of fetal growth. What this really boils down to is that Hudson uses an experimental drug to grow the embryo, so that it can survive outside the mother's womb. The dog, "Number One", grows to adult-size rapidly, and is passed off as its mother.
Hudson lives with his sister-in-law Diane Ladd (as Martha Douglas); since his wife Nicole, also a doctor, died in another car accident. Ms. Ladd seems more emotionally stable about Nicole's death than Hudson, who survived the crash that killed his wife. Things begin to get creepy when Hudson's dog shows an intelligence level far above any normal dog. Then, Hudson decides to use his accelerated embryo growth on a human, Barbara Carrera (as Victoria Spencer).
Hudson and the cast try their best; but, the "Embryo" storyline is wretchedly absurd nonsense. If you take away her silly opening and closing scenes, Ms. Carrera's valiant characterization almost works; she might have been a bigger star, if offered better films than this. The infantile ending suggests a sequel; but, happily, the idea was aborted.