Parents know that when their children are in a different room and all goes quiet, something is up. Wednesday is a quiet day but the plot to kill Jesus is being planned and Jesus is continuing to teach in the Temple.
The chief priests and the elders and gathered in the palace of the high priest. Caiaphas (the high priest) along with the others are planning to arrest Jesus as quietly as possible and then kill Him. They recognise that they cannot do this during the feast of unleavened bread because there are just too many people around. They know that the best way to avoid a major disturbance within the crowd at the arrest of Jesus is for there to be no crowd. Therefore by seeking to arrest Jesus after the feast, those who came to celebrate the feast would have travelled back home. This is a well thought through plan, but one that Jesus already taught about in the parable of the vineyard and tenants. In that parable, Jesus speaks of how they will kill Him just as the tenants killed the son in the parable.
Jesus teaching: Luke 21:37-38
The plot to kill Jesus: Matt 26:3-5; Mark 14:1-2; Luke 22:1-2