The young and the restless spoiler.?

What do you think about this.

This week, Brock returns to Genoa City to prove Katherine's true identity once and for all and Jill is forced to face the truth: she is not Katherine's daughter. When all is said and done, that old rivalry begins to rear its ugly head once more.

"I had some suspicions that was where the story was going," admits Jenne Cooper. "Then Maria Bell told me several things that I had to be aware of so I could prepare for the future, so I sort of knew, but Jess Walton was not aware of what the outcome would be."

"I'm loving it!" Walton declares. "It's going to be real fun. Jill is going to be turning into heck on wheels again! Just the possibility that Katherine and Jill aren't related is stirring up a lot of emotions that she doesn't want to confront."

Up until now, Jill has been in complete denial about not being Katherine's daughter. However, once the truth becomes clear, Jill is incredibly hurt and lashes out in anger.

Ironically, Jill is the one who gets the ball rolling when Nikki suggests that they do another DNA test to prove that the last results were wrong. Jill refuses and insists that Nikki bring Brock back to town to test his DNA against Katherine's. Nikki likes the idea and tells Kay about it.

"Kay is very happy, because she knows this will prove who she is," says Cooper. "Yet she's apprehensive, because she knows Jill is going to go out of her mind about the whole thing. What Kay is frightened of is losing Jill as a daughter. Kay is very sad about that and would like their relationship to remain the same. She and Jill have shared so much. They've had laughter behind their fights. Kay is going to miss that closeness, because they did bond."

When Brock gets to Murphy's trailer, he immediately comes face-to-face with his mother. "Brock has absolutely no doubt whatsoever. He knows immediately Kay is his mother," contends Cooper. They share a very warm reunion. "When Kay sees him, she knows all is well. She won't have to work any harder to prove who she is."

After Brock hears about Katherine's symptoms from before the accident (such as memory loss) he begins to wonder if she has Lyme Disease. Kay gets herself tested and Brock's theory is proven true. His mother has Lyme Disease. Later, Brock calls Jill and begs her to accept the fact that Katherine is alive, regardless of the pending DNA results. They end up crying a lot with each other, but eventually Jill caves and finally decides to see her mother.

"Kay explains she doesn't want things to change between her and Jill just because they're not blood," says Cooper. "But Jill is vitriolic. She's hurt beyond belief and so angry."

When Jill is informed of Katherine's Lyme Disease, she assumes it's a con and blows up on Murphy. "Jill starts insulting Murphy and referring to him as trailer trash," recounts Cooper. "Kay really starts getting insulted. She goes back to being Kay, and Jill realizes it immediately. That kind of fire and venom does not happen with a stranger. Only Jill and Kay can get into those fights."

Says Walton, "It's undeniable to Jill. She suddenly thinks, 'Oh my God! This is Katherine.' This is even before the results come back on Brock's and Katherine's test. Jill gets really upset."

The situation grows even more tense when Jill demands that Katherine stay far away from Billy's wedding. Katherine, of course, refuses to miss the ceremony.

On the day of the wedding, a nervous Jill goes on a bender. "She's very nervous, so she's having a lot of mimosa's. The test results are coming back on the day of the wedding, so Jill is starting to feel what's coming and she's getting lubricated."

Katherine and Jill both end up attending the wedding, but tensions reach a fevered pitch when Nikki shows up to the reception with the results of the latest DNA test. That's when all heck breaks loose and the dark side of Jill finally comes out to play. Says Walton, "The viewers are going to have a good time with all of this."

"Jill starts acting out and name-calling, until Kay finally says, 'Enough!' Then, with the swipe of a hand, it starts..."

Let them eat cake?