Mercy, Mercy Bird, is the mystery writer who writes books -- this series you know well -- under the name of Tobias Wells who writes books using Knute Severson as detective. That's the only hard thing you have to understand in this new case which deals with a Contessa and her barefoot hippies which undercuts a little the just-real-folks-hominess around Wellesley, Mass. . . . Decaffeinated.