Temptation Island host Mark L. Walberg is lighting up the season five dating game—literally.

In E! News' exclusive sneak peek at the USA reality series' July 12 episode, Mark unveils a new twist that shocks the four couples who are putting their love to the test: The first-ever temptation light.

"Here's how it works," he explains in the preview. "When it's on, it looks like that and, when you see that red light, that means that one of your partners in the other villa has given in to temptation. You won't know who it is and you won't know what they've done, but when you see that light come on you know someone in the other villa has given in to temptation."

Introducing a tell-tale sign that one of their significant others has cheated with one of the singles in the singles villa pushes Islander Vanessa Valente's nerves over the edge.

"To not know what that temptation is, it's gut-wrenching," she tells her fellow castmates. "I'm gonna sleep on this couch and watch that light all night long, like, I won't be able to rest."

In her confessional, Vanessa explains how past insecurities in her relationship with boyfriend Roberto Maldonado is what makes the temptation light so frightening.

"I'm really upset because I think about just being hurt again," she admits, "and I already have an inability to be vulnerable and to just let my guard down and be soft and just be gentle. So, now I'm just bracing, just waiting for the pain to hit me and it's not a very good feeling."

However, there's even more to the twist as there's actually a light in both the singles and the couples villas.

"By the way, so you're aware, there's one of these lights in their villa as well," Mark adds. "So, it's safe to say to island is always watching.

See if the 16 singles are able to get the couples to give in to temptation when Temptation Island airs Wednesdays at 9 p.m. Keep reading to meet the entire season five cast.

CITY: Los Angeles, CA  

OCCUPATION: Vanessa: Procurement Manager/Roberto: Nursing Student  

AGE: Vanessa, 34 / Roberto, 24 

Vanessa and Roberto met overseas in Qatar and what they both thought was a one-night stand, ended up turning into a long-term committed relationship.  With a 10-year age gap between them, Vanessa is done wasting her time. She was previously married and is now looking for someone to be the father of her children.  She worries that Roberto is not ready to step up to the plate and Temptation Island is the perfect way to test his loyalty and commitment. Roberto on the other hand is doing all he can to show her that he is mature and committed for the long haul. While they have moved in together and built their lives around each other, they're hoping their time on the island will allow them to find a clear path to get past their conflicts and spend the rest of their lives together.  

CITY: Charleston, SC  

OCCUPATION: Kaitlin: Fitness Studio Owner/ Hall: Leather Sales  

AGE: Kaitlin, 31 / Hall, 35 

Kaitlin and Hall have been dating for eight years and while Hall put a ring on her finger, Kaitlin refuses to set a wedding date. She is hesitant because three years into the relationship Hall broke things off because he was feeling terrified of commitment. Since then, they have made major strides and along with the engagement, they have purchased a house together. However, they seem to be in two different stages of their lives and the baggage of their past keeps coming back to haunt them. Hall is ready to settle down and have kids, while Kaitlin wants to start a business and acclimate to life in Charleston. On the island, Kaitlin and Hall are looking to find clarity on how to move forward. Kaitlin hopes to understand where the disconnect lies while Hall thinks the experience will motivate Kaitlin to finalize their commitment and walk down the aisle. 

CITY: Atlanta, GA  

OCCUPATION: Marisela: Hospital Interpreter/ Christopher: Fitness Instructor  

AGE: Marisela, 24 / Christopher, 30  

Marisela and Christopher have been together for two years. Christopher is a sensitive over communicator while Marisela is a careless free spirit. While they both come from broken homes and have a history of being unfaithful with past partners, Christopher has entered his thirties and ready for marriage and believes Marisela is the one for him. On the other hand, Marisela is indecisive to the idea of marriage even though she believes he is her soulmate. She has also tried to move past Christopher's infidelity but holds on to some resentment still. These underlying frustrations have created a standstill in their relationship and they hope their time on island will bring them closer together. 

CITY: Newark, NJ  

OCCUPATION: Paris: Influencer / Great: Engineer  

AGE: Paris, 23 / Great, 25 

Paris and Great first met on social media after Paris dm'ed him to get his attention. They have been dating for almost two years but struggle to trust one another after a history of cheating. While they are willing to do whatever it takes to make things work between them, they are not yet on the same page. Paris would like to take their relationship to the next level and get engaged soon. It's customary in her Angolan culture to get married young and start a family. Although this is similar to Great's Nigerian culture, he wants to take things a little slower and move in together first. They are optimistic that spending time on the island will help align their timelines.  

(E! and USA are both part of the NBCUniversal family)