After warping back in time to the late 20th century for a glimpse of Earth's past, the Enterprise intercepts a mysterious man who simply calls himself Gary Seven. Although Gary and his ever-present black cat Isis appear like inhabitants of the 20th century, Gary knows what kind of ship he is on and recognizes Spock as a Vulcan, and ascertains that the Enterprise is from the 23rd century. Gary Seven evades security officers and resumes his journey to Earth. Kirk and Spock assume 20th century disguises and pursue him, finding that Gary is a time traveler from the future who is here to influence Earth's history - but whether or not his influence will be benign is another question altogether.
