'Black Panther' review: A sleek Marvel of a kingly superhero

"Just because something works does not mean it cannot be improved."

So says the tech-wizard sister of the title character in "Black Panther." It's an apt credo for this soulful, stirringly acted and pretty terrific movie's place in the Marvel Studios realm.

As a rule, these movies basically work, most of them, even if they sometimes feel more like a product, launched, than a superhero world, imagined.

But co-writer and director Ryan Coogler's film qualifies, handily, as his third consecutive and undeniable success, following the roiling docudrama "Fruitvale Station" (2013) and the improbable, irresistible