Cousins Mike and Kate are at Boston's Fenway Park when the Red Sox's star hitter discovers that his lucky baseball bat has been stolen.

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.

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.

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.

Cousins Mike and Kate must help the Philadelphia Phillies' mascot, the Phillie Phanatic, clear his name after the team's bats begin to suspiciously break during games.

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

In New York City for the annual series between rival teams, the Yankees and the Mets, Mike and Kate investigate a spate of pranks, thefts, and sabotage.

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

"The president's brother is a catcher on the Nationals baseball team, and someone is stealing his equipment! Can Mike and Kate help the commander in chief catch a criminal?"--