There are 4 guests left competing for the $250,000 prize. Cris, Kam, Melina and Lindsey. For the first time, the guests are offered four different locations to investigate Ronnie’s murder. The new mystery area is limited to one guest. The final four must compete for the mystery area to gain an advantage and receive an additional 3 minutes in any other area.
The challenge for the mystery area is in the form of ice. They must stab through a block of ice to free a yellow container. Melina is literally killing it until Kam catches up and wins the challenge. He selects the crime scene. Lindsey and Melina get into a heated discussion on who will get to have the last known whereabouts. Their discussion hits a dead end and Giles hands out envelopes that the killer already prepared for this situation.
Lindsey will go to the last known whereabouts. Melina gets the morgue. Cris will double up with her teammate Kam and investigate the crime scene. Cris doesn’t come up with a lot of information at the pool except discovering that the pool is shrouded with ice blocks. The mystery room gives Kam footage of Ronnie in the hot tub and his ejection to the pool. Lindsey notices an unlabeled substance on the tea tray. Melina finds that Ronnie has a high temperature although he has ice all over him.
The partnership between Cris, Kam and Lindsey has come up short on the information. Melina takes notes about her information and confronts the three. She’s spot-on and makes everyone nervous that she has become a completely different person. Melina feels comfortable and confident that she can take on the partnership.
During the challenge, Melina takes her time with the word search before scouring around the house. Kam is able to solve the word search and finds the clue: "pool equipment". Liquid nitrogen was used to freeze Ronnie in the pool but Kam believes the murder weapon isn’t there. After discussing probable murder weapons, Kam believes that ricin, a highly toxic protein, is the weapon because it is made of castor beans. Struggling to survive, Melina decides to eavesdrop on the three. Unfortunately, the information Melina heard may not be enough for her to survive.
Kam impressed the killer this week. Giles then walks everyone through the murder. Ronnie went to the library to write a letter to Giles explaining who he believes the killer is. The killer sends a maid to deliver some tea to Ronnie. Ronnie unknowingly added ricin to his drink. The killer wanted the best for Ronnie and gave him the hot spa treatment. The spa was rigged with liquid nitrogen set to go off on a timer. The ricin he ingested caused his body temperature to rise to a deadly 105 degrees. The poisonous ricin was the cause of death. Once the timer went off, Ronnie was ejected from the spa into the pool.
Cris and Kam are spared leaving Melina and Lindsey with the scared cards. Everyone assembles by the pool table in the morning; luckily, Lindsey and Melina have survived the night. However, Lindsey is laughing uncontrollably, much to the discomfort and concern of her fellow contestants. The four later discover that there is a limousine outside that they are going to ride in. They are escorted by the maids Beatrice and Sophie into the limo, and are also given gifts. Lindsey and Melina are skeptical to open their gifts, as it could kill them. They then discover that they're champagne glasses, and Kam has the champagne bottle. While they are celebrating, the driver takes a sharp U-turn, alarming and scaring the passengers. They suddenly realize that they never knew who the driver was.
They find themselves back at Rue Manor, and rush inside. In the living room, there is a TV set up. Once turned on, after a couple seconds of static, it reveals Giles tied up and surrounded by guns pointing at him. He calmly says that he's been kidnapped and hidden somewhere in the manor, and it is up to the guests to solve the last mystery to find him, or else he will die. The TV then turns off. All of a sudden, smoke immediately fills the room, and in the midst of the confusion and anarchy, the guests discover that Melina is nowhere to be found...