Andy Wiederhorn, CEO of Fatburger, a "fast casual" restaurant famous for their made-to-order burgers, goes on an undercover journey.

When Eric Casaburi, CEO of Retro Fitness, a franchised full service fitness center, discovers an employee who hates customers and fails to follow directions, it leads to one of the biggest reveals ever on UNDERCOVER BOSS. Also, Casaburi works with an employee who credits Retro Fitness for a major lifestyle change.