did haldain die?

yes he did, it was in an episode where time kept repeating itself till it produced the right outcome,apart from that can't remember anything else

From Serenity:Define interesting...Oh God, oh God,we're all going to die?

The episode is a time to kill when a time traveller comes back to try to right a wrong. In the episode almost eveyone of the main cast is killed but it all works out in the end.

This is one of the better episodes of the series and is actually quite dark, originally being heavily cut to fit the 6pm slot.