A couple of years ago, Josh Bazell made a big impression with his first book, “Beat the Reaper,” a funny and brutal crime novel about Pietro Brnwa, a former mob family member who went into the witness protection program. Brnwa went through medical school and had settled into a big-city hospital job when his past — in the former of mobsters looking for him — caught up with him.

Brnwa is back in Bazell’s sequel, “Wild Thing,” one of the most unusual and rewarding crime novels I’ve read this year.

It works chiefly because Bazell’s sense of humor is as sharp as his sense of justice. The book is harsh — although there’s no moment to equal the scene in “Beat the Reaper” when Brnwa performs impromptu surgery on himself — but also laugh-out-loud funny.

As the book opens, Brnwa is working as a cruise ship physician. For the most part, he’s treating the downtrodden crew for bad teeth and venereal diseases. And he’s looking over his shoulder for any members of the mob family that’s hunting him.

Then Brnwa gets a message from a contact offering him an offbeat but lucrative job: Brnwa would represent a billionaire — the 14th-richest man in the United States — on a hunting trip in the wilds of Minnesota.

It seems that the billionaire wants to know if a lake monster is living in the waters of a remote Minnesota lake, feeding on the occasional swimmer. Brnwa’s scientific background as well as his ability to take care of himself against even supernatural odds makes him a strangely apt choice.

Accompanied by the billionaire’s resident paleontologist, Violet Hurst, Brnwa heads for the northern lake country.

A pleasantly teasing relationship quickly develops between Brnwa and Violet, but the real fun in the book is the group they accompany on the lake monster expedition. There’s a couple of low-grade celebrities, some outdoorsy types and one real-life political figure whose presence lends a bizarre reflection of reality to the story and leaves little doubt about Brnwa’s politics.

I won’t reveal the real-life special guest here — nor will I solve the mystery of the lake monster — but her appearance ably demonstrates the funhouse nature of Bazell’s book. The political figure, that is. Well, and the lake monster too.

One of the most interesting things about the book is the extensive use of footnotes. I don’t remember this from “Beat the Reaper,” but it adds a new level of humor here as Bazell comments and elaborates on his own story.

Part of the fun in this book is also the packaging. The inside front-and-back covers are line drawings that appear to show Brnwa and Violet in a series of adventures: getting chased by a tiger, outrunning a volcano, eluding a werewolf, being waterboarded. The illustrations look like nothing so much as the kind of drawings that decorated old-time Hardy Boys books.

The drawings were just larks, no doubt, inspired ideas that tip the reader off that Bazell’s sense of humor is offbeat.

But I’d be happy if Bazell wrote further adventures of Brnwa and Violet. And I’d love to see them take on that werewolf.