Following the breakdown of the very brief union between Namor and Dr. Doom, the Atlantean prince returned to Hydrobase only to find it under siege by a number of his past villains; Attuma, Tiger Shark and...Dr. Dorcas. Well, the first two would be bad enough...
The villains were expecting them though. They're all gloating and stuff when Betty gives them a verbal middle finger. Chicken-shit that he is, Dorcas backhands her one across the face which wakes up the Avenging Son.
At least you inadvertently created some awesome. The book concludes on the panel below.
Instead, writer Tony Isabella and artists Sal Buscema / Fred Kida rely on the simple act of looking up, silently. Everyone in the fictional room, and reading this book, knows that hell will be unleashed in short order. If I'm a kid reading this in 1975, I can't friggin' wait to get the next issue.
Betty Dean was a not huge deal in the "current" Marvel era. But during Namor's adventures of the 40s and 50s she was a regular presence. They did eventually incorporate her into the silver age continuity and she served as a guardian of sorts to Namorita to the point that Namorita took on Betty's last name of Prentiss.
So Dean meant something and she was killed off in the second issue of a long-forgotten book. Ah well. We can't all go out in a blaze of glory.