Sphere of Death

Jeromy and Beth Cloud were out exercising when Jeromy thought ha saw something disappear in the middle of the lake. "Betty!" he called out, I think someone is in trouble out in the middle of the lake. Did you see something? Yes he answered. Something was on top of the water, now it is gone.
The two borrowed a rowing boat and went out to where Jeromy had seen something in the water. When they came out to the center, where Jeromy had seen something, a large bubble came out of the water and sucked Beth in to it. Beth inside the bubble sunk deep in the water. Will she drown?