A mummers' play is the name given to a kind of traditional folk play performed by amateur actors. In most cases, the mummers, the participants in the play, are male and dress themselves up in fanciful costumes depicting legendary figures, such as St. George or the dragon that he's supposed to have killed.
In The Return of the Native, the good folk of Egdon are getting ready for this year's mummers' play, despite the fact that they have no real feeling for their art, nor any enthusiasm. Eustacia Vye goes one better: she has the very greatest contempt for mummers' plays and mummers, the people who participate in them. Such negative feelings are undoubtedly connected to her overwhelming desire to leave Egdon Heath for good.
Even so, Eustacia still wants to be involved in the first performance of this year's mummers' play. Why? Because the performance will take place at Mrs. Yeobright's Christmas party—to which Eustacia hasn't been invited—and will give her a great opportunity to see Clym.
Eustacia comes up with a plan. For one night only, she's going to take someone's place in the mummers' play. That someone is Charley, a rather naïve young man who positively worships the ground Eustacia walks on.
Eustacia uses her power over Charley to persuade him to let her play the part of the Turkish Knight at the Yeobrights' Christmas party. In return, she will allow the smitten Charley to hold her hand for fifteen minutes. Charley had originally wanted a half-hour, but Eustacia managed to negotiate a better deal for herself.