1. Watching TV with my wife and children in our living room. We live up on a hill on the edge of town. 2. I heard the beating sound of a helicopter coming by. This is fairly common but this time it started to vibrate the whole house so I stepped outside on the deck to observe. Overhead passed a huge helicopter only maybe 100ft directly above. I immediately noticed there was another craft flying next to it but it was black, no lights, no props, no apparent sound. 3. I didn't know what to think. UFO, drone, secret military stuff? 4. The dark craft seemed to be flying under cover of night and under cover of the helicopter. The helicopter was the biggest one I've ever seen. It had a single prop and tail rotar. 5. Surprise, awe. 6. It disappeared into the night and over the horizon.