Crystal Cave

Four young children find a hidden cave that houses a space/time warp. The four embark on a series of adventures, taking them back through time and space. They make three separate visits to the cave and have three distinctly different adventures.
They become trapped in a Saturn V rocket on a journey into space. They also help to search for a prehistoric child who is in grave danger. Then finally, they try to save Queen Cleopatra from kidnappers in ancient Egypt.