What is the main conflict in The Vig by John Lescroart?

In this novel, Hardy is working as a bartender at the Little Shamrock when his former office mate, Rusty Ingraham walks in. It seems that a criminal who threatened to kill them both is scheduled for release from a federal prison. Ingraham is concerned and sets up a calling schedule with Hardy, but misses the first scheduled call. Hardy goes to his barge and finds a bloody crime scene, convincing him that the ex-con has stayed true to his threats. The Vig is a suspenseful novel filled with twists and turns that will keep the reader guessing until the final page.