One normally would not say "lie ahead of someone", but for the example you gave, "lay ahead of them" refers to the looming "peril" in the future. It's a different way of saying that something is in the near future. It can also refer to something being physically close to someone. I don't know if this makes complete sense, but it's quite a hard phrase to explain.

In addition to what Valentine wrote, you'll need to say "something lay ahead/ something lying ahead/ something laid ahead" for the sentence to make sense. That "something" could be anything (good or bad) that is anticipated but still yet unknown. "The hunter was again joined by the same natives that abandoned him, when he described the riches that laid ahead".

Tnx for response The hunter was abandoned by the natives when he described the peril that lay ahead of them.

Where have you seen this? I am a native English speaker and I am not familiar with this term.