Snitch is worried his cat, Mildred, might get stolen, so he hides her in the gang's clubhouse. Snitch's brother, Wizard, tells him nobody would steal Mildred in the first place, but even if they did try, they wouldn't get away with it. After all, he and his buddies--Skinny & Tubby--are private eyes with a clubhouse that's alarmed with a special water-bucket-alarm.
Despite what Wizard says, Snitch wakes up the next morning to find Mildred gone. He's certain someone has stolen her, and the gang is on the case. After a few dead-ends, the detectives finally solve their case, and boy, are they surprised by what they find!
I loved these books when I was little! Love 'em now, too.