18:1-4
Ahab was about the worst king Israel ever had, but Jehoshaphat allied himself with him by marriage. One time when he went to see Ahab, Ahab urged him to join him in attacking Ramoth Gilead. Jehosha phat agreed, but urged him to seek the Lord first.
18:5-8
So Ahab called in the prophets, but these prophets were favourable to the king, and they all encouraged him to attack and that God would give him victory. Jehoshaphat was not fooled, realising that they were not prophets of the Lord. \ahab told him there was still one prophet, but revealed that he did not like him, for he never prophesied anything good about Ahab, this was Micaiah, Jehoshaphat rebuked the king,and Micaiah was summoned.
18:9-15
Ahab and Jehoshaphat were dressed in their royal robes, maybe to impress Micaiah. \the ones who had brought Micaiah urged him to follow the line of the false prophets and to prophesy victory. Initially he does this, but Ahab was not fooled and demanded a true prophecy.