Following in the tradition of other Magic blocks, Ravnica takes place in a plane of the multiverse that was previously unexplored in the game's backstory.
The world of Ravnica is an ecumenopolis, a vast city that covers the entire surface of its planet, and is home to a diverse assortment of sentient races.
[12] Each of the guilds had been at war with each other for centuries, and the only thing that made the leaders agree to a truce was the fact that the dead had begun haunting the plane.
They decided that each guild would specialize in two colors of magic and have specific jobs in the city to stretch the limited resources and maintain order, including by banning war completely.
Agrus Kos (A Wojek officer in the Boros Legion), Jarad (Brother of the Devkarin leader Savra), Fonn Zurich (Daughter of a Wojek officer who joined the Selesnya Conclave after her dad's death), Feather (A Firemane angel who worked with Kos), Pivlic (An Orzhov businessman), and Savra (The leader of the Golgari Devkarin elves) are the main characters in the novel who each play their own role.
The dark undercity's the domain of the Devkarin elves, and that's where Jarad and the rest run the city with necromancy and hunting skill; while the skies above are policed by Boros angels.
They both stay to their own sections, so the Selesnya keep passageways clear with the Ledev, a group of paramilitary soldiers who defend the right of free travel.
With a partner dead (although continuing to appear in the plot in the form of a ghost), Kos embarks on the investigation that takes him throughout the various settings of Ravnica.
With their new friend Teysa Karlov, Orzhov baroness of the diseased frontier zone named Utvara, the two begin to unravel an Izzet secret that delves deeper than any of them thought, all the while searching for the missing messenger of Zomaj Hauc, Izzet Guild upper manager and lead engineer of the Cauldron, a powerplant supplying energy to all of the Utvara region.
Crix the goblin finds herself in the hands of the indigenous peoples of Utvara while Baroness Teysa and her minions attempt to gain control of the region that has now become hers to own.
But Crix finds that the plains around Utvara are mysterious, full of bizarre creatures that trace back to the ancient days of Ravnica, as well as a race of people who wear fungus on their backs to protect themselves from a spore that got thrown up into the air after the Izzet Guild attempted to "reclaim" the Utvaran region for the previous owner, Teysa's uncle and prodigal father.
Meanwhile, unbeknownst to the courier, Agrus Kos and Pivlic have also become aware of the strange behaviors of the natives and begin an expedition to rescue the intrepid Izzet.
However, as they work forward toward their goal, both the human and the imp find that it is not as easy of a task as it originally appeared, especially not when the Nephilim, the ancient creatures Crix encounters, become more rampant in this area of the frontier.
Back in Utvara, things seem to be simple and reclaiming the once lost territory is becoming a task that Teysa Karlov has turned into a lucrative business venture.
He wrote that the guilds "define the landscape and structure of life within Ravnica, and each has a particular function in the city that relates to their color pairing in Magic’s card game.
It also gave a name to all of these tendencies that had already existed in the game for more than a decade, and today when you say 'Dimir,' an enfranchised player is going to know that you mean a combination of blue and black cards.".