Although he is lord of the realm, even the devil doesn’t like hell in John Connolly’s “The Infernals,” the young adult fantasy sequel to “The Gates.” Lightly scolding readers who haven’t read the first book, the narrator kindly provides a brief synopsis to ensure everyone is on the same page, so to speak, in the continuing saga.

The devil, aka the Great Malevolence, tried to escape hell in the first book with a plan that couldn’t fail. “Naturally, it failed spectacularly.” His most trusted servant Ba’al gets blamed, and spends all of “The Infernals” seeking redemption.

The protagonist in both books (or perhaps the antagonist, if you side with the devil) is Samuel Johnson, a small boy ever accompanied by his faithful dachshund, Boswell. It seems that Samuel was aided by the demon Nurd, the Scourge of Five Deities, who thwarted the plan just as the Great Malevolence was about to slip through a portal created by a malfunction in the Large Hadron Collider in Cern, Switzerland.

Physicists there, monkeying around to recreate the Big Bang, which is when everything — including evil — was created, are the ones ultimately responsible for all the mayhem.

But it was Nurd who drove Samuel’s father’s car back through the portal into hell, causing the portal to collapse.

The devil’s failed escape drives him into madness, setting the stage for competing demons in hell to begin assembling their legions of Infernals in the second book to wage battle for ascendancy as heirs to the ailing Great Malevolence.

“All clear?” the narrator asks after the recap of the first book to make sure readers understand what’s going on. So far, so good.

But things get pretty complicated fast. To start, Samuel and Boswell get sucked from Earth through the portal into hell — along with four troublesome dwarfs; an ice cream truck and its driver, Dan the Ice Cream Man; and Constable Peel, Sergeant Rown and their patrol car.

Ba’al — who remains embodied back in hell as Mrs. Abernathy, her cover while on Earth to prepare the way for the evil’s escape, sets out to find and capture Samuel. The hope (something in scant supply in hell) is that presenting Samuel to the Great Malevolence will put her back into the master’s good graces. But Samuel’s courage and cleverness are forces of their own to be reckoned with.

“The Infernals” is a wonderful morality tale delving into the nature of evil, quantum physics, dark matter and the hubris of scientists who play God. That Connolly, a part-time Portland resident, can roll all this into a rollicking tale makes it a delightful treat for young and old readers alike. Although the tale is not billed (yet) as a trilogy, it’s difficult to surmise otherwise, given the ending.

“The Infernals” is satisfying in its own right, but it is reason also to go back and read the first book — and eagerly await the third.

Frank O Smith is a Maine writer, ghost writer and writing coach.