Complex sentence: When Paul, Graeme, Clive, Ruth and Tara arrive at Devils Tower National Monument (a location used in the sci-fi classic "Close Encounters of the Third Kind"), they set off fireworks to use as a signal and wait.
Split into simpler sentences: When Paul, Graeme, Clive, Ruth and Tara arrive at Devils Tower National Monument, a location used in the sci-fi classic "Close Encounters of the Third Kind". They set off fireworks to use as a signal and wait.