A young Russian inventor can not find application for his “truth generator” however, despite the objection of the FSB (modern KGB), a rich buyer appears.

I wonder what you mean by "can't find an application."

Also, what do you mean by "objection of the FSB?" This is a good place to raise the stakes.

You might consider saying "Russian secret police" instead of FSB. You obviously feel the need to explain what the FSB is, but the parenthetical breaks up the rhythm of the line.

sounds intriguing, maybe they buyer is connected to the FSB. Great tagline.