Sarah Jane and her friends meet aliens called the Blathereen and invite them to dinner... but are these aliens as friendly as they seem?
Sarah Jane, Luke, Clyde and Rani want to stop a Slitheen who wants to turn Earth into a giant diamond and sell it. Suddenly two Blathereen appear, arrest the Slitheen and sent him to their ship. They tell Sarah Jane that they are trying to stop the Slitheen from causing harm. Then they ask to have a dinner at Sarah Jane's house. Rani likes the idea and convinces Sarah Jane to do so. Clyde cooks for the Blathereen and they eat together. After the dinner the Blathereen give a Rakweed plant to Sarah Jane. They tell her that she can feed the world with Rakweed and that no one would ever be hungry again. However the Rakweed has poisonous seeds and infects Luke. Luke becomes ill and can't go to school. Rani and Clyde go there alone. They find out that the school bell destroys the Rakweed and tell this Sarah Jane. Sarah Jane asks Mr Smith to make a loud noise all over the city. All Rakweed plants disappear and Luke is feeling better already. Luke says that he hopes that the Blathereen would never come to Earth again.