I still haven't heard a better premise for Indy V than bringing back the haunted castle concept. It's a good fit for Indy, it would cause way less controversy than aliens, it hangs nicely on a pulp fiction hook as Lucas insists (Hammer horror), it doesn't clash with the time period (Hammer was certainly active in the 50s/60s), it promises a return to the spookiness of the first two films, it gets us out of North America, and it doesn't call to mind action sequences that would seem preposterous for a guy in his 70s.
The Fountain of Youth and the Bermuda Triangle are too recently covered by Pirates of the Caribbean and don't sufficiently liberate us from North America after the previous film, Atlantis wouldn't feel fresh enough coming off of a fourth installment that was already about a lost city, and Excalibur would be the second Arthurian legend covered by the series.
The only real concern would be that it might make the movie too claustrophobic, but Temple is a good template here, as it succeeded in delivering some striking location work before pulling us underground. You would just need to front-load the exotic locales.
Last edited by Udvarnoky : 10-20-2016 at 10:54 AM.