At Steep Wisdom, the Ninja are creating a defense system against Ghosts.

Zane puts up a sign "There. That should keep customers away. "Closed for renovations."

Kai sets up a bucket of water on top of the door. "More like fortifications. If Morro and his ghouls show up here looking to steal the Sword of Sanctuary, they won't know what hit them"

Cole almost had the bucket of water fall on him "Aah! Careful, you know not all of us are immune to water. And I for one would like to stick around long enough for Misako and Sensei to figure out the last clue"

"We got Cyclon-do, we got the sword, now they just have to figure out where the Tomb of the First Spinjitzu Master is" Jay says

Kai sighs "Let's hope they figure it out soon. I don't know how long we'll be able to hold out"

Someone steps on a tripline and set off a bell.

"Intruder!" Kai shouts

Everyone catapults water balloons.

"ok... this time I wasn't wearing a bathing suite"

The ninja look out and see Aria.

"Aria" they say happily running over to her

"Welcome back, you've been gone for so long we were staring to get worried" Kai said as he hugged her

"Oh my god, cousin Cole you're a ghost" Aria said seeing Cole

"Yeah but I'm alright" Cole reassured her

"It's good to be home" Aria said "I do have a errand to run before i stay here though, I just thought I'd check in. I'll be back in a couple hours"

"Aw but you just got here" Jay whined

"Sorry" Aria apologized "I promise I'll be back in a couple hours"

-

The Ghosts laugh as Morro releases Ronin from his possession.

Ronin groans "Pretty good impersonation. But they'll never buy it was me. Once the princess comes back you'll be in trouble"

"I plan on her coming back" Morro says

Lloyd is trapped in a cage "You're no Green Ninja. The Green Ninja would never need to lie."

"Oh, you won't be the Green Ninja for long" Morro tells him "Save your strength, because I'll be needing it. Prepare for a voyage. We head to the tomb at dawn."

"Aria's going to kick your ass" Lloyd mumbles

-

After Aria returned, the ninja travel to the Caves of Despair.

"This is where we first came for the Golden Weapons. It's like everything has come full circle" Cole said

"Don't say that. Full circle means it's coming to an end, and I don't want to hear that before I go into the Caves of Despair, one of my least favorite words" Jay whines "How do we even know the tomb's in there?"

"We don't" Aria replied "for all we know it could be another trap"

"Searching for clues" P.I.X.A.L. finds a crudely-carved skull.

"The third symbol" Kai points out

"That's strange" Aria mumbles

Jay shrugs "Good enough for me. Let's go"

"Huh. Looks like it only gets darker the deeper in we go" Cole pointed out as they got deeper into the caves

"Looks like there was a cave-in" Kai said as they approached s

Jay sniffs "Ugh! What's that smell?"

"...Kethanol" Aria answered "it's a highly flammable gas released from deep well mining"

"Look!" Kai pointed ahead "Some of these rocks appear to have been recently moved. Maybe Morro's already been through here. Ash. Everything here has been burned. Perhaps one of the traps?"

"The Kethanol geyser. We cannot stay long. It might ignite again at any moment." Zane warns them

They see a skeleton

"You think it's him?" Jay asjed

"The First Spinjitzu Master" Kai says "Uh, but where's the Realm Crystal?"

"That is not the First Spinjitzu Master" Aria said walking up to the skeleton "It's Morro's, he died here in this cave"

Jay looked around "Well, Sensei told us he never came back from looking for the tomb. So if he's here, that means..."

"It is trap!" Ghoultar shouts coming out of nowhere "Now you suffer same fate!" He uses his scythe to trap them within the cave.

"There's no way out!" Kai shouts "If this was a test, I think we certainly failed it"

Jay coughs "And all this gas is making me a little lightheaded"

"This cavern is a virtual oven. If those geysers decide to ignite, we'll be cooked" Cole said

"P.I.X.A.L. has located an opening. The cave-in must have created a gap." Zane informs them

"Oh, but a gap to where?" Jay asks "For all we know, it could be a dead end and for the record, that's another one of my least favorite words. Dead end"

"Too late!" Cole grabs a boulder and blocks the geyser

"Cole, no!" Aria shouts

"Ha, solved that problem" Cole laughed

"Correction, you made it worse" Zane says "Now the pressure will compact the explosion, multiplying the damage tenfold"

"Oh, what are you trying to say?" Jay asks

"When that rock goes, every cave in a 10-mile radius will be filled with a wall of fire so hot, it'll incinerate everything in its path!" Aria shouts

"Guess we better get hot on our heels" Kai says wraping his arm around Aria's waist "hold on tight"

"Cyclon-do!" Jay shouts and everyone Airjitzus their way out of the gap.

Jay sees Ghoultar and uses his Aeroblade on him "Haha, I caught it, guys! I caught it!"

Suddenly, R.E.X. came by and unraveled a ladder.

"Haha! I could kiss Ronin! After I clobber him for getting us into this mess!" Cole shouts

They climb inside, but Ronin's not there.

"Oh, oh, oh. Autopilot!" Jay shouts "Course he's too scared to show his face"

Ronin appears on screen "Hey, Ninja. If you're getting this message, I'm sure you have some choice words for me. But I want to tell you, that wasn't me who sent you to this trap. I was under the control of Morro. I know you think I'm a crook by taking the sword, and I wanna make things right by offering my airship, R.E.X., as a peace offering. I know it's not what you had in mind, but I've remotely entered the location of the tomb. The real one this time" He shows a map of the Endless Sea.

"Look at that. The reason Misako never found the tomb in Ninjago was because it was never there in the first place. It's under the ocean" Kai says

"Morro has a head start, but R.E.X. should get you straight there in a jiff. And if it's any consolation, this'll be the last you see of me. If Nya wants to know a reason, tell her it's because I care. Oh make sure you don't bring Aria along, I think Morro is planning something bad. Okay. Good luck. And go make things right"

"Oh we all know I'm still coming right?" Aria asked looking around

"Yeah we know you're stubborn" Kai sighs "looks like we're headed to the tomb. Time to buckle up"

Aria flicked Kai's forehead "Hey! I'm not stubborn, I'm just determined"