A couple who have no recollection of how they got there find themselves in a lethally dangerous environment where every creature and several of the plants seem to be trying to kill them. Being religious, they realize they are lost souls and this must be hell.
Then the search party finds them. They were vacationing in Australia and had wandered off after someone gave them roofies.
But what happened in between that would make and amnesiac tourist decide that they were just in the eternal pit. -- Bard2DBone
Mary woke up pressed and oppressed between burning heat and sharp stones riddled with ants that were painfully pinching her flesh. It took her far too long to get away from the ants. There was no escaping the heat. It scorched her throat. The harsh light seared her eyes. The sharp ground tormented her feet. There were creatures that looked like they were made out of thorns. Everything plant-like here looked like it was dead. Everything alive here was seemingly made to hurt.
The sky was bare of clouds. The earth was bare of anything friendly to Mary's means of classification. Only a pair of windswept tyre tracks gave any indication of how she got here. And there were lizards the size of dogs ambling through this tortuous landscape. Mary picked the direction least likely to intersect with the lizards and tried to logically conclude something from established facts.
Fact: It was burning hot. Fact: there was no water to be seen but the wavering illusions on the horizon. Fact: The plants appeared to be dead. Fact: The livestock was outright hostile or at least appeared to be so. Fact: Everything here was made to hurt her. Fact: The last thing she remembered before waking up here was a rather sinful hen's party. Conclusion: She must have died and gone to Hell.