I was driving with my son to go deer hunting in southern illinois. we took i-55 south to cape girardeau and crossed the mississippi there. it was around 10 pm and we were on illinois route 3 heading south about to run parallel to the river. i noticed a strange looking plane coming from the east moving at a very slow speed. i saw it but didn't think much about it until it shot down behind some trees at an amazing speed. it moved so fast my eyes couldn't follow it. i was blown away by what i had just seen but also confused. then the object shot back up from behind the trees, hovered for a few seconds, shot up some more and then flew off towards the direction it came (east). the speed that this thing was capable of was insane. it moved so fast it was almost like it would jump locations instead of smooth movements. the whole incident left me confused by what i had witnessed and a little nervous.