This collection includes:

Ballpark Mysteries #6: The Wrigley Riddle: Ivy-covered walls--they're the most famous part of the Chicago Cubs' historic ballpark, Wrigley Field. Mike and Kate can't wait to get down on the field to see the ivy for themselves. But when they do, they're horrified to discover patches of the ivy have been ripped away! Who would want to sabotage the stadium?

Ballpark Mysteries #7: The San Francisco Splash: Splash! A hit soars over the walls of the San Francisco ballpark on the bay and drops into the water. But then Mike and Kate hear another, much larger splash nearby...and this time it's not a baseball. It's a man overboard! And when he's pulled from the water, the old-time ballplayer discovers his World Series ring is gone!

Ballpark Mysteries #8: The Missing Marlin: Mike and Kate are in Miami, visiting Kate's Uncle Oliver--and the Miami Marlins ballpark, of course! Uncle Oliver is in charge of keeping the new fish tanks at the ballpark fully stocked, but strange things keep happening. Kate swears she saw an endangered sea turtle in one of the tanks. Then some of Uncle Oliver's rare fish go missing, including his favorite, Marlin.

Ballpark Mysteries #9: The Philly Fake: What better city to spend the Fourth of July in than Philadelphia? For Mike and Kate, the holiday is all about hot dogs, history, and baseball! But the Phillies are in no mood to celebrate. They keep losing, and some people blame the lovable Phillie Phanatic.

Ballpark Mysteries #10: The Rookie Blue Jay: Mike and Kate can't wait to watch their rookie hero, Dusty Martin, in action. But something is throwing the Blue Jays' star off his game. Then, when no one else is looking, Mike sees mysterious ghost lights flying across the field.