The ongoing fued between Lisa Vanderpump and Stassi Schroeder is about to explode in "Vanderpump Rules" season 4 episode 21, the first "Reunion" episode this season. According to a report from US Magazine, the argument will arise when Vanderpump brings up the issue of Schroeder's sex tape and how Vanderpump resolved it.

As stated in the report, their current issue began when Schroeder's ex-boyfriend threatened to release a sex tape involving him and Schroeder, a move which would not only affect Schroeder but also Vanderpump and the Sur business. 

In order to take control of the situation, Vanderpump paid off Schroeder's ex. The ramifications of this action did not sit well with Schroeder, particularly after Vanderpump and Ken Todd decided to approach Schroeder's parents and ask for compensation.

"You and Ken Todd had gone to my parents and told us, 'You owe me 900 dollars,'" Schroeder is heard complaining in the official preview clip for the episode. Vanderpump fires back, stating that she was only trying to save Schroeder from the actions of her ex-boyfriend. 

The argument continues to rise and it is indicated that not only will harsh words be flying about but the two leading ladies may even begin getting physical, to the point of punching or slapping each other over the issue. 

However, this will only be a part of the episode. As the episode title suggests, several old and familiar faces will be making a return, and as stated in the official synopsis for "Reuinon" by Bravo TV, a few revelations will be made as well. In particular, the episode will reveal who among the ladies had gotten intimate with other females on the show.

As it turns out, an "overwhelming" number of the ladies had gotten into relationships with the other females on "Vanderpump Rules," an issue Vanderpump will bring up in the episode.

"Vanderpump Rules" season 4 episode 21 airs this March 21.