Tim Rackley, a deputy U. S. Marshal, and his partner nicknamed Bear, are given the assignment to track down Walker and take him into custody. They start by searching Walker’s cell. Tim figures out how Walker escaped seemingly into thin air, but there are few personal items that provide any clues to why a model prisoner with little time remaining on his sentence would break out of prison. He’s a former Marine sniper, married but long separated, his only family an older sister Tess. He and his father have not spoken for years. A photo shows that he and Tim look a lot alike.

Further investigation reveals that Tess, Walker’s sister, committed suicide a short time earlier. Her seven-year-old son Sam, suffering from a rare genetic disease, is being cared for by Kaitlin, Walker’s estranged wife. So far, the only cure for the disease is a liver transplant, a long shot. Tess had tried to get Sam into drug trials of an experimental treatment.

The company developing the treatment, Vector, is run by Dean Kagan and his CEO son Chase; another son Dolan is a researcher involved in the development. Tess had turned herself into an expert on treatment and experimental drugs. Shortly after Sam was dropped from the drug trials, Tess died from a gunshot wound to the head.

Walker starts uncovering secrets about Tess and Vector and sets out to avenge Tess’s death. Tim and the Marshals Service are always a step behind as the body count mounts. What is the truth behind Tess’s death? Can Tim catch Walker before it’s too late?

Neatly categorizing this book into either a police procedural mystery or a thriller is impossible because it straddles both genres. From Tim Rackley’s perspective it may be a police procedural, but from Walker Jameson’s it bears a strong likeness to thrillers such as Lee Child’s Jack Reacher novels, whose hero he somewhat resembles. It’s both a whodunit and a what happens next.

Tim is the hero first introduced in The Kill Clause, followed by The Program and Troubleshooter. Tim and his wife, Dray, who’s on extended maternity leave, have a two-year-old son Tyler. He’s been in a somewhat similar position to Walker – he turned vigilante after the murder of his little daughter – and there are other parallels in their lives. Tim fully understands and sympathizes with Tess’s determination to save her son and admires her accomplishments. In fact, as Tim learns more about Walker, Tess and Vector, he realizes he even likes Walker. He’s conflicted even as he tries to anticipate Walker’s next move knowing that in a showdown he may have to kill him.

To a certain extent, Tim and Walker are co-heroes. The real villains are the power-, money-grubbing company and the morality-challenged Kagans and their cohorts. They’re stock characters. Super-rich corporate tycoons are commonly evil in fiction. All that wealth and power don’t come without a price.

.Last Shot is a worthy addition to the Tim Rackley series. (I have to ask: is the title a clue that this is the final installment?) The high-paced action doesn’t come at the expense of character motivation. Readers who haven’t read the others won’t be lost in Last Shot, but it helps to have the full back story. The best advice is to read them all. They all deserve high recommendations.

--Lesley Dunlap