Plus: Get an exclusive look at the cover, and read the first chapter!
But his current series,The Trials of Apollo, is a little different.
With the help of a half-blood daughter of Demeter named Meg, Apollo/Lester has successfully reignited two Oracles.

Credit: Johnny Louis/Getty Images; Disney
The Labyrinth weaves itself under the skin of the world, Riordan tells EW.
It can take you anywhere, assuming you dont get lost or killed by monsters or traps.
I just love the idea of a secret, unpredictable underworld that you might fall into at any minute.

Disney
Bringing back Grover is like getting to visit an old friend from high school, Riordan says.
Writing about Grover is so natural and comfortable for me.
Hes taken on some serious responsibilities… like saving the entire southern half of California from climate disaster.
But fans shouldnt worry about the series sustainability; there are still plenty of stories to tell.
Im always amazed at the depth of Greek and Roman mythology, Riordan says.
The more I delve into it, the more I find.
Below, check out the cover forThe Burning Mazeand read the first chapter.
The book hits shelves on May 1.
Excerpt fromThe Burning Mazeby Rick Riordan
1.
Once was Apollo
Now a rat in the Labrinth
Send help.
I refuse to share this part of my story.
It was the lowest, most humiliating, most awful week in my four thousand plus years of life.
I will not tell you about it.
Why are you still here?
But alas, I suppose I have no choice.
Doubtless, Zeusexpectsme to tell you the story as part of my punishment.
Its not even enough that he enslaved mehisformerly favorite sonto a pushy twelve-year-old demigod named Meg!
On top of all that, Zeus wants me to record my shame for posterity.
But I have warned you.
In these pages, only suffering awaits.
With Grover and Meg, of course.
The Labyrinth could be a bewildering place.
(like dont ask.
It was traumatic.)
I would have preferred to avoid the Labyrinth altogether.
Except that our cloven guide, the satyr Grover Underwood, did not seem to know the way.
Youre lost, I said, for the fortieth time.
A red knit cap covered his curly hair.
Why he thought this disguise helped him better pass for human, I couldnt say.
The bumps of his horns were clearly visible beneath the hat.
He stopped at a T in the corridor.
In either direction, rough-hewn stone walls marched into darkness.
Grover tugged his wispy goatee.
Like me, he had quickly come to fear Megs displeasure.
Not that Meg McCaffreylookedterrifying.
Cobwebs streaked her dark pageboy haircut.
The lenses of her cat-eye glasses were so grimy I couldnt imagine how she could see.
Grover pointed to the tunnel on the right.
IIm pretty sure Palm Springs is that way.
Like last time, when we walked into a bathroom and surprised a Cyclops on the toilet?
That wasnt my fault!
Besides, this directionsmellsright.
Meg sniffed the air.
I dont smell cacti.
Meg, I said, the satyr is supposed to be our guide.
We dont have much choice but to trust him.
Thanks for the vote of confidence.
Life was not fair.
Meg wiped her nose.
I just didnt think wed be wandering around down here for two days.
The new moon is in
Three more days, I said, cutting her off.
Perhaps I was too brusque, but I didnt need a reminder about the other part of the prophecy.
I tried to soften my tone.
We have to assume Leo and the Romans can handle whatevers coming in the north.
We have our own task.
And plenty of our own fires.
As he had for the last two days, Grover remained evasive.
Best not to talk about it .
He glanced around nervously as if the walls might have ears, which was a distinct possibility.
The Labyrinth was a living structure.
Grover scratched his ribs.
Ill take a stab at get us there fast, guys, he promised.
But the Labyrinth has a mind of its own.
Last time I was here, with Percy .
I couldnt blame him.
Percy was a handy demigod to have around.
Unfortunately, he was not as easy to summon from a tomato patch as our satyr guide had been.
I placed my hand on Grovers shoulder.
We know youre doing your best.
We followed our guide down the right-hand tunnel.
Soon the passage narrowed, forcing us to crouch and waddle in single file.
I stayed in the middle, the safest place to be.
Allegedly, he had great powers, though I hadnt seen him use any yet.
I, on the other hand, had grown weaker and more defenseless by the day.
My fingers had grown sluggish on the fret board of my combat ukulele.
My archery skills had deteriorated.
Id even missed a shot when I fired at that Cyclops on the toilet.
(Im not sure which of us had been more embarrassed.)
At the same time, the waking visions that sometimes paralyzed me had become more frequent and more intense.
I hadnt shared my concerns with my friends.
I wanted to believe my powers were simply recharging.
Our trials in Indianapolis had nearly destroyed me, after all.
But there was another possibility.
I had fallen from Olympus and crash-landed in a Manhattan dumpster in January.
It was now March.
That meant I had been human for about two months.
Had it been that way the last two times Zeus exiled me to earth?
Dont youdaretell her I said that.)
I tried to ignore it.
The last few times Id asked the arrow for advice, it had been unhelpful.
Id never liked the 90s.
(By which I mean the 1590s.)
Perhaps I would confer with the arrow when we made it to Palm Springs.Ifwe made it to Palm Springs .
Grover stopped at another T.
He sniffed to the right, then the left.
His nose quivered like a rabbit that had just smelled a dog.
Suddenly he yelled Back!
and threw himself into reverse.
Before I could complain that I dontdogroup massage, my ears popped.
All the moisture was sucked out of the air.
possibly from the blood boiling in my head.
My mouth was so dry it was impossible to swallow.
I couldnt tell if I was trembling uncontrollably, or if all three of us were.
I wondered why my first instinct had been to saywho.
Something about that blast had felt horribly familiar.
In the lingering bitter smoke, I thought I detected the stench of hatred, frustration, and hunger.
Grovers red knit hat steamed.
He smelled of burnt goat hair.
That, he said weakly, means were getting close.
We need to hurry.
Like Ive beensaying, Meg grumbled.
She kneed me in the butt.
I struggled to rise, at least as far as I could in the cramped tunnel.
With the fire gone, my skin felt clammy.
If wed been caught in that blast, we wouldve been ionized into plasma.
Well have to go left, Grover decided.
Um, I said, left is the direction from which the fire came.
Its also the quickest way.
Guys, were close, Grover insisted.
But weve wandered intohispart of the maze.
If we dont hurry
Screee!
The noise echoed from the corridor behind us.
SCREEE!The second cry was angrier, and much closer.
I didnt like what Grover had said about us being inhis partof the maze.
Run, Meg said.
Run, Grover agreed.
We bolted down the left-hand tunnel.
At the next crossroads, we turned left again, then took an immediate right.
SCREEE!it cried from the darkness.
I knew that sound, but my faulty human memory couldnt place it.
Some sort of avian creature.
Nothing cute like a parakeet or a cockatoo.
Something from the infernal regionsdangerous, bloodthirsty, very cranky.
We emerged in a circular chamber that looked like the bottom of a giant well.
A narrow ramp spiraled up the side of the rough brick wall.
What might be at the top, I couldnt tell.
I saw no other exits.
The cry grated against the bones of my middle ear.
The flutter of wings echoed from the corridor behind usor was I hearingmultiplebirds?
Did these things travel in flocks?
I had encountered them before.
Confound it, I shouldknowthis!
Grover stared into the gloom above, his mouth hanging open.
This doesnt make any sense.
This shouldnt be here.
No, I said, the back of my neck tingling with dread.
We wont make it.
We need to block this corridor.
But
Magic plant stuff!
One thing I will say for Meg: when you need plant stuff done magically, shes your girl.
Grover whipped out his panpipe.
Together, the lord of the Wild and the daughter of Demeter made a super gardening duo.
The seeds erupted into tomato plants.
Their stems grew, interweaving across the mouth of the tunnel.
Leaves unfurled with ultra-speed.
Tomatoes swelled into fist-size red fruits.
The tunnel was almost closed off when a dark feathery shape burst through a gap in the net.
Talons raked my left cheek as the bird flew past, narrowly missing my eye.
No, it was twice as big as Athenas largest specimens.
Its plumage glistened obsidian black.
My sight grew fuzzy.
My knees turned to rubber.
Apollo, you okay?
Strix, I said, the name floating up from the recesses of my feeble mortal mind.
That thing is a strix.
How do we kill it?
Always the practical one.
I touched the cuts on my face.
I could feel neither my cheek nor my fingers.
Well, killing it could be a problem.
Grover yelped as the strixes outside screamed and threw themselves at the plants.
Guys, weve got six or seven more trying to get in.
These tomatoes arent going to hold them.
Apollo, answer me right now, Meg ordered.
What do I need to do?
I wanted to comply.
Really, I did.
But I was having trouble forming words.
K-killing the bird will curse you, I said finally.
And if Idontkill it?
Oh, then it will dis-disembowel you, drink your blood, and eat your flesh.
I grinned, though I had a feeling I hadnt said anything funny.
Also, dont let a strix scratch you.
By way of demonstration, I fell over sideways.
Above us, the strix spread its wings and swooped down.