Kent State: Andy & Mark and the Time Machine

In the fourth book of the series, Amy uses the time machine to observe the most famous anti-war demonstration of the Vietnam War era. Her objective: uncover the mystery surrounding the controversial shooting of Kent State University students. But Amy miscalculates and finds herself staring down the rifle muzzles of the Ohio National Guard as they are about to fire! Determined to find and rescue their friend, Andy and Mark embark on a journey in time that takes them through those fateful day...