The series featured an unlicensed private investigator named Jim Hardman, a white ex-cop who works with a black partner, Hump Evans, a former pro football player.
[4] The first seven Hardman novels featured cover art by Scottish artist Ken Barr, who drew comics for DC and Marvel.
The final book to be published during his lifetime, 1979's MacTaggart’s War, was his only hardcover sale; Kirkus Reviews called it a "sweeping adventure spectacle… Dennis is a spiffy storyteller".
[4] Brash Books subsequently reissued all twelve of the Hardman novels, with new introductions by Joe R. Lansdale, Paul Bishop, Mel Odom, Robert J. Randisi and former Georgia U.S. Representative Ben Jones among others.
[14] In a review of the reissued Atlanta Deathwatch, Publishers Weekly wrote, "Dennis pulls no punches in this lightning-paced crime story packed with irreverence and loads of action",[15] while Mystery Scene called it "lean and mean, with punchy descriptions and sharp-edged dialogue", and described Dennis as "a crime writer whose work has been criminally undervalued".
"[17] The magazine also praised The Spy in a Box, one of his previously unpublished manuscripts, as "a disciplined focus on atmosphere...Dennis’s stark, impassive prose will appeal to noir fans.
Publishers Weekly praised the book, writing: "In lesser hands, this kind of hard-boiled style would fall into cliché or stereotype, but Dennis, with a sharp ear for dialogue, skilled plotting, and the ability to create fully developed characters, keeps the story fresh and the action believable.
But a long-lost, unpublished Hardman novel, All Kinds of Ugly, was discovered by Lee Goldberg in late 2019 and was released by Brash Books in February 2020.
Publishers Weekly said in its review that All Kinds of Ugly demonstrated that Dennis' "strong prose and well-paced storytelling place him alongside the likes of George V. Higgins and Ross Macdonald.".