After finding a powerful ring, a man working a white-collar job must keep the magical relic from a greedy, other dimensional man in order to save the world.

Sounds promising, although personally I am tired of movies about Powerful Rings... :)

Why is the 'man working a white-collar job' an interesting character? He feels fairly bland. Perhaps you're doing the 'ordinary man' meets 'extraordinary circumstances'? Still, I want to be intrigued by the character as well. Frodo was interesting because he's not just a mere mortal. He's a Hobbit!

The other issue is 'keep the magical relic from a ... man': this is an open-ended goal. Give us a specific way of saving the world and while this action is underway, he must keep the ring. Saving by just keeping is not particularly interesting.

But I assume he will ultimately need to kill/return the 'other dimensional man'. Perhaps include the moment that triggers this need in the logline. Most likely this will become the mid point as sometimes an open-ended goal becomes specific halfway the movie.