Jill Trent, Science Sleuth

In trying to class Jill into the superhero types of the 1940s the closet you can get is "bored socialite turned to adventurer."

Except that unlike those other rich girls, it would seem that Jill made all that money herself. She's also hard to class as bored. She always seems to be inventing something or saving her girlfriend fellow sleuth from kidnappers. She's all brains with no powers or masks, but she never fails to face the bad guys down with a cool head and some random object she just built. (MacGyver would approve; real science, I am not so sure.)

Her to-be-hostage-in-less-than-eight-pages pal is Daisy. Despite her awful luck of always getting grabbed, she's no pushover. You might have a knife to her throat now, but she will be kicking you in the head later. Hard. In fact, Jill and Daisy both have a habit of beating the living daylights out of the bad guys that mess with them.

Jill Trent got started in Fighting Yank #6. I've never come access a copy, and it hasn't been reprinted.  I haven't heard anything about this one, but I doubt it is an origin story. She just doesn't seem the origin story type.

Her earliest appearance that has made it to the net is Fighting Yank #9 (August 1944), "Case of the Sanitary Murders." All the art is by Al Camy. I have no idea who wrote any of them. 

Fighting Yank # 9 page 39 //40 //41 //42 //43//44 //45 //46

After two issues in Fight Yank Jill Trent moved to Wonder comics, running in #8 to #20. You can go here and read Jill's story from Wonder Comics #13.