As Jesus is teaching in the temple, the priests set the wheels of their conspiracy in motion. First, they ask him under whose authority he's teaching. Jesus counters with a riddle of his own: was John the Baptist's authority human or divine? The elders put their heads together and conclude that if they say it was human, the people will stone them, but if they say divine, he'll ask why they didn't believe him. So they don't answer the question and neither does Jesus.
Turning away from the time-wasting nincompoops, Jesus starts to tell a story about a rich man who decides to rent his farm out and go on holiday. Why are these stories always about rich people? Are they like our tabloid magazines? Did people back then want to fantasize about being rich, just like now? Anyway, the rich man sends a rent collector after the harvest, who is beaten by the tenants. A second, then a third collector meet the same fate. Next, he sends his son, believing him beloved by the tenants. Not so much, as they kill him. Finally, the man comes back in person and kills all the tenants and finds new ones. The disciples are rightfully horrified, so Jesus retorts What is this then that is written, The stone which the builders rejected, the same is become the head of the corner? (v. 20) Then he threatens to either drop people or have them dropped on the stone.
That lovely little parable finally prompts the priestly decision to arrest Jesus, but they hesitate at first because he's so popular. They send out spies to find evidence of blasphemy.
First they ask if they should pay their taxes. For the record, the answer is yes, no matter what a Republican presidential candidate tells you, you should pay your taxes. Then the Sadducees ask what will happen to a woman who marries seven brothers and is widowed seven times: whose bride will she be in heaven? Answer, in heaven you won't have to hold aspirin between your knees because there won't be any sex. This stops all the questions, but Jesus has a question of his own: why do people say the Messiah will be one of David's great-great-great grandkids, when David himself calls the Messiah Lord? Finally he warns the people to be wary of vain priests who cheat people out of their property, because they will be punished.