The cover of this issue shows Supergirl unconscious, in the arms of some costumed stranger. The name of the story if 'Bride of the Stars'. There are no KO scenes in the actual story. The cover is very nicely drawn!
Supergirl is captured in a kryptonite cage by Braniac (flown by a flying saucer, or UFO), and is then forced to breathe kryptonite gas!
She is able to escape because the cage bars are too big.
Supergirl is gassed while investigating some creature in the woods. She is captured, and shown bound in some contraption in the next issue.
Don't worry, she is rescued in the same issue.