Once again, author Darby Karchut shows off her amazing knack for building on each installment of a series, making each book better than the last.

In the Adventures of Finn MacCullen series, Ms. Karchut hasn’t struck a bad note yet, but the third book—“The Hound at The Gate”—surpasses even its two predecessors.

The first two novels mainly focus on the relationship between apprentice Finn “Don’t Call Me Finnegan” MacCullen and his Knight, Gideon Lir. We watch as Finn struggles to learn all the skills required to make him a full-blown knight in the ancient Tuatha De Danaan realm.

The first novel—“Finn Finnegan”—shows Finn’s early training, and the dangers that surround this world so new to Finn. The second novel—“Gideon’s Spear”—shows Finn come into his own, gaining confidence and skill, and showing the traits that will make him a brave warrior in his own right.

In the third installment, “The Hound at The Gate,” Ms. Karchut shifts gears a bit. Rather than focusing solely on Gideon and Finn, she gives us a glimpse into the entire Tuatha De Danaan world.

The location is The Festival, a gathering of Tuatha De Danaan from all over. It’s a sort of ancient warrior Woodstock, with feasts, music, and challenges, a chance for Knights and Apprentices to renew old friendships, and—especially for Gideon and Finn—some old rivalries.

Also attending The Festival—crashing the gates is more like it—are the Amandan, fierce goblin-like creatures whose favorite food happens to be Tuatha De Danaan.

Things turn ugly early, as certain people question Finn’s right to attend The Festival, since he comes from a Knight father and a mortal mother. This internecine tension crackles throughout “The Hound at The Gate,” as if the Amandan weren’t enemy enough.

Repeatedly, Finn finds himself locked in combat for his life and that of his friends.

And those were the good times.

On one night of The Festival, the unthinkable happens. A massive army of Amandan force the Tuatha De Danaan to retreat. Things look hopeless. Only incredible bravery by a handful of Knights stands between being vanquished or living to see another morning.

As the battle winds down, Finn becomes embroiled in yet another quarrel regarding his status, this time due to his uniqueness, not his difference. At stake is his future as a trainee, and the chance that he could be forever separated from his beloved mentor, Gideon.

I can’t stress enough how much of a page-turner “The Hound at The Gate” is. I’ve learned better than to start one of Ms. Karchut’s novels before bedtime, since I know I’ll read all night, and never get any sleep.

As interesting as the lives of the Tuatha De Danaan are in the first two novels, “The Hound at The Gate” gives us a broader glimpse into this mythical world. We see the alliances and rivalries within the group. We learn about the hierarchy and ruling body, and we see all of these things disappear when the Amandan mount a full-scale attack. Knights and apprentices work together, regardless of position or personal feelings. There’s a job to do, and each is prepared to defend the group to his or her dying breath.

I say “his or her” advisedly, because one of the highlights in this novel is the introduction of a feisty female Knight named Kel, and her equally feisty apprentice. Needless to say, these two women leave Gideon and Finn utterly flummoxed, even as they more than prove themselves equals to the men in the group.

Ms. Karchut does a wonderful job providing rich description, setting a visual stage against which the battle will be fought. Then she lets fly with the action.

“The Hound at The Gate” is my favorite thus far of the “Adventures of Finn MacCullen” series, primarily because of the expanded view it gives of the warrior group. While the action is plentiful and powerful, I like the quieter moments as well. Here, we see the people behind the flashing daggers and swinging axes. We can see our own groups mirrored in the Tuatha De Danaan, with all of humankind’s foibles, strengths, and weaknesses.

We also see how all of Gideon’s training has rubbed off on Finn. Not just on the battlefield, but in other areas as well.

Like the rest of The Adventures of Finn MacCullen series, “The Hound at The Gate” is classified as a “middle-grade” book. Also like the rest of the series, “The Hound at The Gate” serves as an excellent read for adults, too.

My only complaint is that Ms. Karchut is making us wait till 2016 for the next installment. That’s a long time to wait for such an exciting series.

Most Highly Recommended

(nb: I received an Advance Reader Copy of this book from the publisher)