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.

"While they are kayaking outside the San Francisco Giants' ballpark, Mike and Kate rescue an old ballplayer who has fallen overboard and discover his World Series ring is missing"--

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.

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 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 when someone tries to stop the Cooperstown team from participating in the Little League World Series in Williamsport, Pennsylvania.

"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?"--

"Babe Ruth's baseball glove goes missing before a Baltimore Orioles game. It's up to cousins Mike and Kate to find its whereabouts"--

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.