When Alvin sees a sparkling diamond buried in his neighbor's rose garden, he's sure she's responsible for the recent diamond heist. So, with the help of Theodore and a VERY reluctant Simon, Alvin sets about proving it.
Alvin is practicing for a skate championship when he crashes into Miss Croner's roses. Shortly after she bans him from her yard, Alvin injures his leg. At home, Alvin hears of a diamond robbery on the radio and is convinced she's the thief. His brothers and Dave go to dinner while The Chipettes watch over him. Once they go downstairs, Alvin sees suspicious activity at their neighbor's. The next morning Alvin spots something shiny in Miss Croner's yard so he sends Theodore to investigate. After she hears Theodore, she confronts Dave while Theodore explores her house. Needing more time, Alvin forces Simon to stall her. Theodore is caught snooping in the basement and is captured. Alvin rushes over to save him only to learn he is fine and Miss Croner is cheating in growing her roses for the competition. Alvin apologizes by giving her a rose bush and the ruby she lost in her garden. He invites her to his championship where he wins first place.
- First appearance of Simon's hidden cabinet safes.
- Alvin spying on a neighbor who he thinks is a jewel thief from his window while his leg is broken is a reference to the Alfred Hitchcock film Rear Window.
- Alvin's line "She's like a T-Rex. She can only see you if you move." is a reference to the film Jurassic Park.
- Part of the Alvin's Wild Adventures and Summer of Sport DVDs.
- Miss Croner's first appearance in the series.