Our main character is Cassius Green (Lakeith Stanfield), driven by poverty to take a job as a telemarketer. After a couple days of failure, one of his co-workers (Danny Glover) suggests he try using his "white voice." He turns out to be spectacularly good at that, and is soon promoted to the much more lucrative "Power Caller" floor - just as all his friends among the telemarketers are taking job action against their employer, which he declines to join.
What that description doesn't include is the surreality of the movie: the least of which is when he makes a call he's suddenly sitting face-to-face with the person on the other end of the line (including when they're on the toilet or having sex). And "white voice" is achieved by over-dubbing: Cassius is white-voiced by David Cross, another employee is white-voiced by Patton Oswalt. And then there's the slavery and re-engineering of humanity by the world's biggest corporation ... All as our hero goes on a surprisingly traditional philosophical voyage to realize it's wrong to do anything for money.
I found the movie kind of fascinating because of the its sheer weirdness, but most critics thought the movie was very funny. I get that it was meant to be, but the humour didn't really work for me.