Two in a Boat

Three children and their Grandpa are on a kayak-outdoor trip in the middle of nowhere. What was supposed to be a relaxed summer weekend with some nice small adventures turns into serious trouble when their Grandpa suffers a heart attack in the middle of the wilderness. Nobody can hear the children screaming, the mobile phone has no net, nobody is in sight or even close. The children are completely on their own - with an old man in a small boat who does not move any more and is barely breathing.