LOYALTY. By Ingrid Thoft. G.P. Putnam’s Sons. 405 pages. $25.95.

In the hard-boiled detective genre, new authors are always popping up with what they hope is the great detective novel, with the toughest detective, grittiest story and so on. Most of them fail.

In her debut novel, Ingrid Thoft has not failed. Maybe she hasn’t quite achieved greatness, but “Loyalty” certainly ranks as pretty darn good.

Private investigator Fina Ludlow’s sister-in-law is missing. Her brother, Rand, is a suspect in the disappearance, which he doesn’t seem at all upset by, and Ludlow’s family of Boston lawyers expects her to deal with it. And by deal with it, they mean keep the dirt from hitting the family, even when Rand Ludlow is charged after his wife’s body is found.

Fina Ludlow is tough, and she has to deal not only with the people trying to keep her from solving the case, but with her family, which has some less-than-admirable members.

Thoft delivers good writing, a truly fine mystery with credible motives and emotions, and really believable characters, many of which fall into two categories: those who readers will want to shoot and those they’ll look forward to seeing in Thoft’s next book.

Reviewer Carol Edwards is a freelance editor and farmer living in Marlboro County.

THE EXPLANATION FOR EVERYTHING. By Lauren Grodstein. Algonquin Books. 335 pages. $24.95.

This story is just too nice. And in most of the ways you can take that phrase.

A biology professor has made his name as a humanistic evolutionist while fumbling through a life of unreconciled guilt and the grieving void left by the wife he loved, who was killed in a car wreck.

A few hard-core Christian students hatch a plan to have him direct an independent study for one of them on the science of intelligent design. They see it as a way to have him confront the Eternal Presence. He sees it as a way to force the student to apply the rigor of scientific inquiry.

Then he gets a mad crush on the sweet-faced student he directs. And there are his daughters, the “just friends” neighbor, a few other tortured souls and an imminent tenure decision.

Lauren Grodstein pops the characters against each other like metal balls in a Newton’s cradle to explore the disparate viewpoints. A dark vein of tragedy gets exposed late in the story that opens the raw issue.

But for the most part, tragedy keeps a degree of separation from the characters’ action. The resolutions get a little too pat. The characters lack some subtleties, and some dimension in the semblance of their beliefs.

Grodstein does make intimate play of finding common ground across one of the divisive issues of our time. She spins a good human yarn, if thin in spots. “The Explanation for Everything” might not be all that. But it is ... nice.

Reviewer Bo Petersen is a reporter at The Post and Courier.