Horrid Henry's House Party is the twenty-eighth episode of Series 2.
Great Aunt Greta comes to look after the boys, so naturally Henry takes advantage of the situation.
Dad comes to the house where Peter and Mum are making fairy cakes, Henry is trying out the Peter-Propeller. Later Henry's parents are gone with Great Aunt Greta taking care of Henry and Peter, Greta gets muddled up with everything. Later some of Henry's friends have a party in his bedroom, then the episode ends with Greta and Peter on the floor thanks to the Peter-Propeller and Dad getting into trouble with the Police.