Volunteering at a local soup kitchen, Polo gets to know Scratchy, a self-described "sidewalk architect." With a Food for Vets sign in hand, Scratchy spends his days at his "office," a freeway off-ramp in downtown San Francisco, where certain drivers are exceptionally generous. Scratchy asks Polo to check the license-plate numbers of the charitably-minded individuals, and Polo comes up with a multimillionaire shipowner and a mysterious ex-CIA agent. But before he can give Scratchy the information, the man is dead, the apparent victim of a hit-and-run. The police have little interest in the accidental death of a homeless man, so at the urging of the soup kitchen's operator, Father Tomasello, Polo decides to investigate. What he finds takes him up against the Dragon Head of the Chinese Mafia, whose connections with the shipping magnate and the ex-CIA agent threaten not only Polo, but his friends and family too.