Herod Antipas, having killed John the Baptist, seems to be having a guilty conscience. He wonders if Jesus might be John redivivus, manifesting powers that someone like that might manifest.
Then follows a flashback story of how John died. He was imprisoned for being a gadfly, challenging the tetrarch about his incestuous marriage.
The marriage of Antipas and Herodias would probably not raise an eyebrow today. That says more about us than them.
Herodias wants John to die, but Antipas is fearful of public reaction. She finds a way to get her way. John is beheaded
The leaderless disciples of John take his body and bury him, then go to tell Jesus about what happened.
The heroes of this story meet an untimely and grisly end. That’s what you call foreshadowing.