Bright red light leading a helicopter at night.I heard a helicopter flying toward my direction and decided to step outside to watch it fly overhead. I heard the helicopter and saw its navigation lights quite clearly (it was dark and no moonlight, breezy, but no clouds), and noted it was on a heading of about 196 degrees True (checked with my compass), therefore flying towards Butte, MT. I could not make out any identification numbers (too dark). Leading in front of the helicopter was a fairly bright red light, about the size of a dime from my vantage point, which was leading the helicopter by 100-200 yards. This was a single red light, constant, not strobing, and without accompanying green or white lights - just a solitary red light moving in unison with the helicopter. At the time I felt that I could see both objects quite clearly. I believe I heard only one helicopter fly over. After perhaps 10 seconds, both disappeared into the distance. Both were perhaps 1000 -1500 feet in altitude above my position.! What I saw immediately struck me as an odd scene, and one that I could not readily explain. It just did not appear to be another helicopter leading the one which I could see very clearly.