I have no way to communicate with Earth.
If the Oxygenator breaks down, I’ll suffocate. If the Water Reclaimer breaks down, I’ll die of thirst. If the Habitat breaches, I’ll just kind of explode.
If none of those things happen, I’ll eventually run out of food and starve to death.
The third Mars mission has had to evacuate and return home because of a dangerously strong storm. Due to a freak accident, Mark Watney is left for dead. But he’s not dead. And now he’s alone on Mars, without enough food, air, or energy to last the many months it would take rescue to arrive. Not that he can call for help. Nevertheless, he is an engineer…
Watney is competent and resourceful, and he does have resources to be resourceful with: all the equipment the crew left behind when they abandoned Mars. Mars keeps throwing problems at him, and he keeps figuring out solutions, knowing that the first problem he can't solve will kill him for sure.
What makes this fun is all the engineering (although I’m sure it’s much harder than shown here); the little acid comments Watney keeps making about the entertainment choices of his departed crewmates; and the potatoes.
I am surprised that Watney didn’t realise that Earth would be able to see that he was still alive, but much of the rest of it rings sufficiently true to make this a thrilling adventure across the Red Planet.