The hit NBC drama “Medium,” which airs Mondays from 10-11 p.m. EST, has gathered a massive fan base in its fourth season.

“We have such devoted fans,” said Patricia Arquette, who plays Allison Dubois on the show.

In the show Dubois, a loving wife and mother of three, has incredible psychic abilities that enable her to work within the criminal justice system. Dubois, who works in an attorney’s office, can speak to dead people, dream of violent events from the past and receive visions of the future. The show is entertaining and suspenseful due to its dramatic plot twists and the nature of her unpredictable psychic episodes.

The relationship of the Dubois family is very close and warm, much like Arquette’s real-life relationship with her siblings.

On April 7, Patricia Arquette’s older sister, Rosanna Arquette, makes a guest appearance on “Medium” in an episode called “Lady Killer.”

The show will feature Rosanna as a devious, attractive killer who seduces young men and commits violent crimes. The episode will contain many brutal love scenes and dream sequences.

“I dream about Rosanna, the femme fatale, a lot in the episode,” Patricia said.

Rosanna, who is eight years older than Patricia, has appeared in more than 70 feature films including “Crash” and “Pulp Fiction.” She most recently worked as part of the cast on “What About Brian,” a show on ABC.

“It was difficult playing a villain in the episode because I’ve never done anything like it,” Rosanna said.

Rosanna and Patricia have a great relationship, enabling them to work well together.

“When we were younger, the eight-year age difference made it difficult, but as we got older we became very close,” Rosanna said.

The two have been on screen together in the past, in the 2002 documentary “Searching for Debra Winger.” The sisters said they had a lot of fun working on the “Medium” episode.

“I kept smiling because Rosanna was cracking me up,” Patricia said.

For die-hard fans, which account for most viewers of the show, the Arquette-sisters episode will be one not to miss.

Patricia said she is very happy about the success of the show.

“I’m always excited and surprised by what the writers come up with, and I really hope there will be a fifth season,” she said.

All of the Arquette siblings are actors, so there might be another Arquette guest appearance on “Medium.”

“David has actually directed two episodes, and I would love for him to be on the show,” Patricia said.

“My siblings and I all know each other so well,” she said, “so we are open to exploring as actors, and there is a collaborative exchange of ideas between us.”

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