Whiz Tanner and the Wounded Pigeon

It's Spring. It's Saturday. School is out in two weeks. Life is good. Joey Dent and his best friend Whiz Tanner are on a leisurely bike ride when they find an injured bird under a tree. The bird happens to be a carrier pigeon wounded by a shotgun. The pigeon is also carrying a mysterious coded message!
The Tanner -Dent Detective Agency is back with a new case to solve. Can Agents M and K handle it, or will this case prove to be the downfall of our young heroes?
And while we are asking, who are Bluesky and Greensea?