*** "Spartan Gold" (Fargo series) by Clive Cussler "with" Grant Blackwood features brave attractive American philanthropic treasure-hunter couple trailed by commandos from sadistic murdering Russian, simple motives. Both contenders have deep pockets and global resources. I admire the adrenalin adventure; the complex puzzle annoys and bores. My favorite part is holidays to vast scenic jaunts: Florida swamp, dungeon oubliette, Alpine meadow, bigwig shindig, Nazi cavern sub outpost, Venice's San Marco Plaza.
But would conqueror Napoleon secrete clues to a gold fortune in hidden wine bottles, a flimsy buried paper codebook, and obscure trivia riddle verse? Could modern technology and researchers still find and solve surviving remnants? The premise doesn't synch, I would sit out the search with the Emporer's son.
Dangerous exploration and close escapes apply physics, geometry, and mechanics, always by the husband. At least the wife responds to urgent commands and doesn't argue, how some writers mistake equality.
The final fate of the villain is anti-climactic ["Do you like heights?"], at least the good guys don't continue to leave evil alive. I know real life is not fair, criminals survive victims, so I like justice to triumph in fiction.)