The duo were 'abducted' yesterday along with Liz Jones, Lee Ryan and Jasmine Waltz and spent the night sleeping in the spaceship in the garden.
Today, Jim and Luisa were given earpieces and told to return to the house, tasked with collecting some of their fellow housemates' belongings.
However, Dappy will be called to the Diary Room and told by Big Brother that the aliens have an evil plan to invade, which he and a housemate of his choice must thwart.
The other housemates will be told to keep Jim and Luisa distracted so that Dappy and his accomplice can sneak into the spaceship to take down the mainframe.
The duo will activate a security system when they enter the craft, and will have to destroy the mainframe before the timer runs out.
First, they must destroy 'alien egg pods' on the ceiling by using tools to smash them up, which will release a "disgusting gunge" and activate the alien mainframe.
They must then crack the security password by correctly answering three questions about their fellow housemates, but if they answer incorrectly the abducted celebrities will receive a shock.
The housemates will win the luxury shopping budget if they correctly destroy the alien mainframe in time.
Celebrity Big Brother continues tonight at 9pm on Channel 5.