Megan Atwood 
Stay in the Game [PDF ebook] 

The prize: $10 million The rules: Be the first to complete ten tasks assigned by the Benefactor. Do not ask questions. Do not tell anyone what you’re doing. Do not fail. The consequences: Unknown James’s grandpa is dying. An experimental treatment has a chance of saving him, but James’s family can’t afford it. Not unless James competes in the Contest. The rules are sketchy, and the tasks seem dangerous…and definitely wrong. James has the feeling this contest is about a lot more than the prize money. But he can’t back out now can he?