No Other Choice

The worst One-Way Path known to fiction.

When a character must do something as they have no other available option at that moment. This "something" the character must do is usually an undesirable action, such as killing one of their friends to proceed in a task, or stand around and do nothing as they are stuck in prison or another Inescapable Trap. When there is No Other Option, there is often some hesitation to move forward even though moving forward is the only thing the playing character can do. If there being No Other Option doesn't mean the character can't choose what they want to do next, then it may instead mean that they are forced down a One-Way Path that typically leads to that character's death. The thing that pushes the character forward might be a Killer Boulder, Angry Mob, or Killer Monster that chases the character down a single, narrow road they must continue to rush down if they want to continue living.

There are times when there actually are other choices, but all decisions except one that a character can make are illogical and can only end up causing more damage than if the character stuck to the one real option they had. This could mean teaming up with the enemy as working alone is ineffective and will only result in an Unhappy Ending. More often than not, the one put in this situation is an antagonist who must cooperate with the Good Guys or Main Cast to Save The Day as not doing so will hurt the antagonist along with everyone else.