January 2, 2012, on an island close to the legendary location of Atlantis (which, ironically, is also called Atlantis), a mining crew is blasting explosives to create a mineshaft. Suddenly, three rocks fall out from a wall - a fossil, a carving, and a symbol of a flame. The miners plan to take the fossils to a museum. However, when the fossils touch a burning torch, a Cistecephalus activates!
Later, the Beta Pack is seen, roaming the mines in search of that therapsid. Obviously tired and hungry, the Beta Pack (or the B-Team for short) are on the verge of quitting, when suddenly the Cistecephalus passed by behind them, and the fleeing miners begin to trample the B-Team.
Back at Max's house, Max is watchin TV when Compy comes in and tells Max that he's recieved a video call. It was Zoe, who told Max to turn on the news. He does so, and is shocked to see the fiery red therapsid terrorizing the nearby mining town. Worried, he and Compy rush to the D-Lab to tell Reese.
Reese identifies the creature as the Cistocephalus, a relative of the Diictodon, but it was smaller and was a carnivore. Reese then remembers how Compy can help the D-Team teleport anywhere in the world. Soon, in the click of a mouse, Rex, Max, Zoe and Compy, are in Atlantis.
Soon, the B-Team are near the mine entrance, chasing the hepless Cistecephalus. Max comments about the "old lady" Mursula, who actually makes a scene right in front of the D-Team. Mander and Med try to calm her down, but to no avail.
Suddenly, Mursula crouches down and grabs something - the Fire Stone! It was connected to the Cistecephalus' fossil but was broken up by the miners. Then Mursula glows with a red light, meaning she now has the power to control Fire Creatures. Then she does something unexpected - she touches a stone tablet with a picture of an erupting volcano onto the Fire Stone!
Unexpectedly, the Cistecephalus' mouth started to burn up in flames, which it threw in the direction of the D-Team! Good thing they were able to duck. Compy then identifies the Move as "Volcano Burst". Reacting quickly, Zoe then summons Dicky.
The Cistecephalus is about to use Volcano Burst again, but Dicky was able to use Thorn Whip and succesfully defeat the Cistocephalus. However, Mursula has claimed its card and nicknamed her "Sister". Now the D-Team has to go home sad, without a new creature fosill or a precious Atlantean souvenir!