Time gate

THE FOURTH DIMENSION had finally been opened up, thanks to the invention of the Time Gate. Now man could journey into the dim past or venture into the far-distant future. But the Time Gate had to be kept a top-secret project, manned only by Tom and Cal Linstrum and a few carefully selected scientists—for in the wrong hands, it could become the most potent weapon yet created. Traveling through time, even one man could alter history enough so that everyone on Earth would simply cease to exist. Of course, it would never happen because only a madman would even try to distort the time stream. Then one horrifying day, it did happen. And Tom and Cal found themselves chasing through a rapidly changing panorama of history, trying desperately to capture their enemy before they and their whole world vanished forever...!