Doors of Sleep

What would you do if you woke up and found yourself in a parallel universe under an alien sky? This is the question Zax Delatree must answer every time he closes his eyes.
Every time Zax Delatree falls asleep, he travels to a new reality. He has no control over his destination and never knows what he will see when he opens his eyes. Sometimes he wakes up in technological utopias, and other times in the bombed-out ruins of collapsed civilizations. All he has to live by are his wits and the small aides he has picked up along the way - technological advantages from techno-utopias, sedatives to escape dangerous worlds, and stimulants to extend his stay in pleasant ones.
Thankfully, Zax isn't always alone. He can take people with him, if they're unconscious in his arms when he falls asleep. But someone unwelcome is on his tail, and they are after something that Zax cannot spare - the blood running through his veins, the power to travel through worlds...