Kemp is promising some shock and awe in the war being waged among the characters in her popular Starz drama.
"Never trust anyone," Kemp told CNN with a laugh.
Filled with plot twists and turns, "Power" follows a New York club owner who is living a complicated double life.
Kemp said you ain't seen nothing yet.
"When you're done watching the show this season you're going to be...I don't want to say enraged," Kemp said. "Shocked. That's the word."
The beginning of the season finds James "Ghost" St. Patrick (played by Omari Hardwick) incarcerated for murder, put there by the woman he loves, Assistant U.S. Attorney Angela Valdes (played by Lela Loren).
While Ghost struggles in jail, his best friend Tommy Egan (Joseph Sikora) is trying to keep their drug empire afloat, while also helping Ghost's wife Tasha (Naturi Naughton) deal with trouble at home.
That's not even including the tension going on with Ghost's nemesis, believed to be dead Kanan (50 Cent), who has sunk his hooks into Ghost's teen son Tariq (Michael Rainey Jr.).
Kemp is known for keeping her characters on the edge and teased this season will be even more intense.
"It's gotten harder to write, and I think it's gotten harder to watch," she said. "Not in a way that it's not a pleasure to watch, but I think it's a pleasure to watch and it's also a little bit of suffering because you know the stakes are so high and you know that any of your favorite characters can be dead at any moment."
Things are certainly rougher for Ghost, Omari Hardwick told CNN, as more layers of the character are revealed.
"It's a credit to Courtney and the rest of the writers," Hardwick said. "It's a very dubious task to play this character day in and day out."
Hardwick added that he thinks the character of Tasha, Ghost's wife and literal partner in crime, has seen the most development since the show's debut.
He praised his co-star, Naturi Naughton.
"Naturi has grown," Hardwick said. "She was the baby of the four [lead actors] and she's really embraced some of the things I have whispered to her, and grabbed the reigns of some of the things I've challenged her with."
Naughton told CNN that "Power" fans are going to see a different side of Tasha in Season 4.
"The whole team of writers have given me such juicy stuff to dig into this season," she said. "I feel like people really misjudged Tasha in Season 1 and thought she was just money hungry and with Ghost for the drug money and the lifestyle. This season you are going to see how much she's sacrificed to keep her family together."
Tasha will also have a new love interest. But one thing you won't see, Naughton promised, is her life playing out on the show's.
While Naughton is due to deliver her first child in July, Tasha won't be adding to her family.
"No, Tasha isn't having a baby," Naughton clarified. "So many people are wondering about that."
Tasha isn't the only one getting a new honey this season.
Joseph Sikora told CNN that Tommy will have some steamy scenes, challenging Hardwick's reign as the actor most likely to be naked in an episode.
"My body is just not as nice as Omari's, but I think Tommy's got a lot of energy and a lot of swag," Sikora quipped. "As with a lot of other areas in his life, when Tommy's with a woman he's very present to her, and I think that that comes across on the screen."
While Tommy and Ghost suffered a schism in Season 3, Sikora said there's still love between the characters.
"I feel like they will always be together, but it will never be the same."
Lela Loren, who plays Angela, said Season 4 will bring more mess.
"Everybody has their own agenda and that makes 'Power' a dark world," she said. "There aren't any really clean characters."
Her character, Loren added, will try not to be "deluded" by her affection for Ghost, who she believes to be a killer.
But will Ghost and Angela find their way back to each other?
"I don't know, even now," Loren said. "The romantic in me hopes they can, but there's still so much story to tell."
"Power" returns at 9 p.m. on Sunday, June 25.