Apple is the most valuable brand on the planet, making products that consumers love to buy. But how does this company treat its workers, when the world isn't looking? The BBC's Panorama program goes undercover inside the factory in China that makes the big-selling Apple iPhone 6. There we see the price paid by Chinese workers on the production line. Apple has made a series of promises that are supposed to protect the workers in factories that supply products for the company. Those promises are comprehensive and involve guarantees about working conditions, even detailing minimum standards of accommodation for workers who have travelled hundreds of miles to work in these factories. Under-cover cameras, though, show a very different picture. Employees are treated like they are prisoners. They are threatened and forced to sign work sheets that show them agreeing to long hours of overtime. Many fall asleep at the end of long shifts, making the work environment dangerous for themselves and others. But it isn't just the factories that turn out the products that create questionable conditions for health and safety.