S04E17: 'It's A Terrible Lie'

The Winchesters have entered a parallel universe where they both lead mundane, normal lives and have no clue who each other are.

Dean Smith is the director of sales and marketing at a large company, dedicated to a healthy lifestyle and meeting deadlines, while Sam Wesson works for the technical support staff in a deadend job.

But, after a spate of co-workers begin to take their own lives after visiting a mysterious room, the boys find themselves working together to try to solve the mystery. The only problem is, they have no idea what to do.

Stumbling across the advice of an unlikely past duo, the brothers soon suspect that the demon is the workaholic founder of the company, a man who demands perfection from his employees and is willing to kill if they make the smallest error.