the most eerie, yet interesting, unsolved cases/mysteries or deaths warning: all true stories. some may be unpleasant. - #2 in thrillers 6/8/19

We have finally done what no other human has ever done before; set foot on another planet. Four astronauts have landed and lived on Mars for three months. The mission is a huge success, and just before they head home they are asked to go and investigate a water source in a deep cave. What they find could explain the origins of the human race...