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.

"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?"--

Mike and Kate's next mystery is legendary! The great baseball legend Babe Ruth's first team was in Baltimore, so the Orioles' ballpark has one of his gloves on display. While Mike and Kate are eating pancakes with the Orioles' pitcher, the glove goes missing. The only clue they have is a gold coin . . . which points back to the pancake-eating pitcher! But how could he have done it? It will take more snacks at the ballpark, a talking parrot, and expert...

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.

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 investigate after Marco and Pedro, the twin batters from the Minnesota Twins, are subjected to a water-balloon attack"--

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

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.

Mike and Kate are volunteering in Cooperstown, helping wrap gifts for needy families, when a very valuable baseball card disappears, and they have a new mystery to solve.

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.