While visiting New York's Yankee Stadium with Kate's mother, cousins Mike and Kate decide to investigate the rumor that the ghost of Babe Ruth is haunting the stadium.

While visiting Houston, Texas, Mike and Kate tour the Johnson Space Center with an astronaut in the morning and at the Houston Astros' ball game that evening, the cousins search for the person who steals the astronaut's moonrock when he arrives at the stadium to sign autographs.

During a visit to the Chicago Cubs' Wrigley field, cousins Mike and Kate investigate why someone has been tampering with the famous ivy vines growing on the outfield walls. Includes historical note.

"Mike and Kate are visiting the Miami Marlins ballpark when some rare animals from the ballpark's fish tanks go missing"--

Through the window of their hotel room in the Toronto Blue Jays baseball stadium, cousins Mike and Kate spot strange blue lights flashing across the bullpen and decide to investigate.

Cousins Mike and Kate set out to catch the person who is selling counterfeit baseball shirts in the Texas Rangers' ballpark.

Cousins Mike and Kate investigate after someone threatens to tamper with the scoreboard right before the Colorado Rockies' season opener.

When cousins Mike and Kate discover that the bat and ball that Hank Aaron used to hit his 715th home run have gone missing from the Atlanta Braves ballpark, apparently by someone who wants the Braves' manager fired--Mike and Kate are determined to solve the mystery and get the stolen artifacts back.