Mike Tampa owns a vineyard in northern California... his land alone is worth $2 million, but he loves wine-making and is not considering selling. His father started the vineyards, handed them down to him, and he hopes that his son Johnny Tampa will be the third generation. Mike Tampa, however, has been the victim of three murder attempts—in the last one, his brakes were tampered with, and he barely survived when he took his car down a mountain road.

At this point, his secretary calls on Cannon—secretly, because the stubborn Mike has refused to do anything. Cannon is brought in to investigate. We learn that Johnny Tampa had only been re-united with Mike two years ago... after not having seen him for 20 years (Mike and his wife went through a bitter divorce 22 years prior and she took their son down to San Francisco).

Cannon suspects that Johnny may be pulling a con and that he is not really Mike's son. The winery accountant says that they had Johnny checked out by a PI down in SF n

Not a vocation, more like a calling. Cannon is mistaken for a bishop's assassin.