Anna, Sam and Barbara participate in a bigamous marriage. They are poisoned into unconsciousness.
When they awaken; each finds themself enclosed in a soundproof room.
Anna and Barbara cannot see either of the others and are totally unaware of the state of the others. Sam can see Barbara and Anna.
Sam is given the following option and given 15 seconds to make a decision:
He has 2 levers in front of him. One is marked "Anna", the other is marked "Barbara." If Sam pulls the "Anna" lever, Anna and he will be released, and Barbara will die an excruciatingly painful death which Sam will witness from the booth before he is set free.
If Sam pulls the "Barbara" lever, he and Barbara will be released and Anna will die an excruciatingly painful death which Sam will witness from his booth before he is released.
Anna and Barbara will be unaware of Sam's dilemna and/or decisions and final outcome. If Sam chooses to pull no lever, both Barbara and Anna will die excruciatingly painful deaths which he will witness. He will then be freed.
What does Sam do?