When a mysterious stranger hires an adept journalist in a mind investigation firm, he discovers the shocking truth – his life is but a dream world wrought by his new boss, Satan, and forced to choose between his lover and career.

This logline is confusing.
1: The logline does not tell us who the “He” is. You have a mysterious stranger and an adept journalist, then you say, he, but do not say which ‘he’ you mean.

In order to clarify this you should try writing it more along the lines of:
“When he’s hired by a mysterious stranger, an adept journalist working for a mind investigation firm discovers…”

2: The logline does not address the central problem.
a: Problem: He is living in a dream world
b: Solution: Must choose between career and lover?
So the solution of choosing between career and lover doesn’t solve the problem of living in a dream world.

Anyway, hope this helped, the first problem is easily fixed with a little shuffling of words, the second problem is more difficult since I don’t know the full story, I am not sure what the solution is.