The Honeymoon Phase follows the journey of Tom and Eve as they enter a social experiment that is supposed to analyze the effects of love on individuals. The couple, who are struggling to make their relationship work, sees this opportunity as a way to strengthen their bond and earn some cash at the same time. They are made to believe that they will be staying in a luxury apartment while participating in the experiment, but things begin to get complicated when they discover that the facility is more than what meets the eye.
The first few days of the experiment seem to be going well, and Tom and Eve find themselves enjoying the peace and quiet as well as the company of each other. However, things begin to take a dark turn when they start to experience strange hallucinations and brutal nightmares. The couple realizes that they are not alone in the facility and that the experiment they are participating in is far more dangerous than they were led to believe.
As time passes, Tom and Eve's love for one another is put to the test, as they struggle to keep their relationship afloat amidst the chaos and terror that surrounds them. They have to work together to unravel the secrets of the experiment, and escape before it's too late. The movie highlights the power of love and the human spirit, as well as the horrors that can come with the pursuit of knowledge.