Clara Schicksal and her brother Hans Schicksal are the co-villains in Richard Jacoma's 1978 novel "Yellow Peril: The Adventures of Sir John Weymouth-Smythe". (available at Amazon)
The Schicksals are pre-WWII Nazi archeologists sent by Hitler to find Die Heilige Lanze, the "Spear of Destiny". They (and several Nazi thugs) are opposed by lone British secret agent Smythe in a cat-and-mouse quest. (This plot idea may have been the basis for the Indiana Jones movies as well as other fictional "Spear of Destiny" themes like the "Dr. Dare" stories in Penthouse Comix.)
Smythe's first encounter with the Nazis (all traveling under false pretenses):
"... at the very gangplank of the riverboat! My car made the quay with but moments to spare. I shouted the Moslem porters into tossing my luggage in the hold, then raced myself for the first-class ramp, trampling my way through the ever-present hordes of massing Asiatics. Just as I gained the ramp's bottom, I collided with another passenger likewise racing, and near sent that person sprawling. In the last instant I reached out, caught a flailing arm just in the nick, and suddenly found myself staring full in the face of . . . the most beautiful blonde goddess I had ever seen! "So sorry!" I panted. "After you, madam." The gorgeous creature I'd almost bowled over was near as tall as I.
A broad, white smile danced on her open face, crinkling her small, fine nose. "Danke mein Herr" she said, and at once turned her attention to a figure lounging on the railing above. "Hans!! she called, and waved a long, suntanned arm vigorously. The man who was the object of her attentions was dressed impeccably in white summer suit and wide-brimmed hat. He was well over six foot tall and well muscled. While his face was tanned and rugged, his handsome, fine features spoke loud and clear of Teutonic aristocracy. The broad smile which he returned to the girl showed plainly that theirs was a blood relationship of more than nationality . And then the Valkyrie was striding up the plank in front of me. I caught myself gazing with much appreciation at the deliciously firm flanks which flared beneath her loose, ankle-length bush skirt. "I'll lose you yet, Clara' the man chided good-naturedly, still in German. "And you'll spend the rest of your days in the harem of some greasy pasha! "Sorry, brother dear! she returned in the same tongue. "Some fantastic architecture from the medieval period." I made my way up the gangplank myself, stepping on board just as the chattering half-naked crew hoisted it and cast off from the crowded quay. I remember feeling, in my damp and dust-coated traveling suit, quite the inferior to these crisp Nordic super humans who strolled obliviously away from me and down the deck."
Smythe soon finds out about the Nazis' quest and first-hand about Clara's perversions that include occult sex ("like the ancient Aryans") and anal intercourse.