Trigon: The Riddle of the Keys centers around three youngsters in three different time periods who find themselves on the outskirts of their communities. Hakim was captured as a slave and forced to work in a mine. Boyd was a big, clumsy fellow who was thought to be a dimwit, but is really very fearful. Arin is an albino who has been so emotionally hurt by her village that she has created a hard shell around herself, making her headstrong, independent, and arrogant. These three children, however, have had one person in each of their lives who cared about them. Arin had Brianna, an herb woman; Hakim had a clever wizard named Emit; and Boyd had a loyal dog.

These three loners eventually face a great evil in their world. They are given three keys and a riddle to solve, which will defeat the great demon for good. Yet, each of them thinks that the key and riddle will help them find the one person who cared for them. As the book unfolds, the children must undertake several difficult challenges. There are hazards, monsters, and personal fears and weaknesses.

Robling uses the traditional elements of folk tales: three tasks, three tools or objects (here keys), three lessons. Like those tales, character development takes a back seat to the challenges that need to be overcome. Robling excels in setting tasks for his characters. In the end, they learn about themselves, think of others, and use some clever thinking. It is a good beginning to a new series.

Robling is currently working on his second Trigon book, Trigon: The Riddle of the Book.