An ancient secret may cause the permanent rift in the relationship of the Mikaelson brothers in the upcoming episode of The CW series "The Originals."

In "The Axeman's Letter," Cartermatt reports that the volatile truce between Klaus (Joseph Morgan) and Elijah (Daniel Gillies) may be ending for good after a very old secret surfaces. This information will reportedly be huge enough to send even the Originals in a frenzy. Does it have something to do with Aurora de Martel (Rebecca Breeds), the mysterious woman who will pay Klaus an unexpected visit? It is clear that the two shared a very long history. Aurora may know something that her past lover had been keeping from his siblings.

Things are steadily becoming grimmer for the Mikaelsons due to the brewing war among the sire lines. Elijah is likewise busy trying to figure out what Tristan (guest star Oliver Auckland) is really after for coming to New Orleans. He believes Tristan is hiding something and he fears that it has everything to do with the fall of the Originals. Elijah will reportedly ask help from Marcel (Charles Michael Davis) to find out his true motives. Will this alliance work out?

Meanwhile, Davina's (Danielle Campbell) role as Regent is starting to get on her nerves. She is reportedly struggling trying to manage everything, but is failing for some reason. In her desperation, she will seek some much needed advice from Hayley (Phoebe Tonkin). Will the werewolf be of any assistance to her? Hayley is battling her own share of problems, what with the complications with daughter Hope.

Last episode, Klaus discovered why Marcel wanted to join the Strix. He said that he wanted to go undercover to learn how the ancient group wanted to kill the hybrid. Marcel feared that once Klaus dies, he would also be a goner. Elsewhere, Elijah and Hayley were about to find out Alexis' (Stephanie Cleough) vision about Klaus. But when they bit her, all they saw were blurry images. It turned out that the witch was poisoned by Tristan's little sister. As to who ordered her to do this, they still do not know.

"The Originals" airs Thursdays at 9 p.m. EST on The CW.