When an mysterious artifact appears on the black market, a pair of dealers must outsmart the criminals of the city’s underworld in order to attain it.

I can see what will happen in the film, but I'm left wondering if the protagonist "dealers" are part of the underworld or are they bona-fide vendors who are now going to find themselves in waters too deep for their liking.

Anytime I see the word "mysterious" in a logline, I see a problem.

How does the artefact impact the main characters? Is it purley a financial interest or is there more? The artefact appearing doesn't make for a very good inciting incident, is there something else that happens that motivates the main characters to have to take action?

Lastly, why two MCs would the story not work just as well with one? If so best to re work it to be about one character.

What's so special about the "mysterious artifact" that it makes it so desirable that it becomes a McGuffin everyone covets? ?IOW: what's at stake? What is gained by possessing it? ?Lost by failing to acquire it?

What is the artefact's worth? Why and what do they want with the artefact?

This is nit picky though, beyond that I see the film and how it could play out.

Whats up with the ALL CAPS?! Bit disconcerting don't you think?
;)