Chapters 18-20 are replicated, to a considerable extent, in Isaiah 36-38.
Hezekiah Becomes King of Judah, 1-12
18:1 In the third year of the reign of Israel’s King Hoshea son of Elah, Ahaz’s son Hezekiah became king over Judah. 18:2 He was twenty-five years old when he began to reign, and he reigned twenty-nine years in Jerusalem. His mother was Abi, the daughter of Zechariah. 18:3 He did what the LORD approved, just as his ancestor David had done. 18:4 He eliminated the high places, smashed the sacred pillars to bits, and cut down the Asherah pole. He also demolished the bronze serpent that Moses had made, for up to that time the Israelites had been offering incense to it; it was called Nehushtan. 18:5 He trusted in the LORD God of Israel; in this regard there was none like him among the kings of Judah either before or after. 18:6 He was loyal to the LORD and did not abandon him. He obeyed the commandments which the LORD had given to Moses. 18:7 The LORD was with him; he succeeded in all his endeavors. He rebelled against the king of Assyria and refused to submit to him. 18:8 He defeated the Philistines as far as Gaza and its territory, from the watchtower to the city fortress.
He trusted in the LORD God of Israel; in this regard there was none like him among the kings of Judah either before or after – Three kings are described as incomporable:
‘Solomon is lauded for unparalleled wisdom and wealth, Hezekiah for unparalleled trust, and Josiah for unparalleled reforms.’ (G.N. Knoppers, cited by Olley)
From the watchtower to the city fortress – In 2019, the remains of a watchtower dating to the time of Hezekiah were discovered on a hilltop in southern Israel. It is thought to be a watchtower that was abandoned when Assyrian King Sennacherib invaded the area in 701 BC at the end of King Hezekiah’s reign. (Source) 
18:9 In the fourth year of King Hezekiah’s reign (it was the seventh year of the reign of Israel’s King Hoshea, son of Elah), King Shalmaneser of Assyria marched up against Samaria and besieged it. 18:10 After three years he captured it (in the sixth year of Hezekiah’s reign); in the ninth year of King Hoshea’s reign over Israel Samaria was captured. 18:11 The king of Assyria deported the people of Israel to Assyria. He settled them in Halah, along the Habor (the river of Gozan), and in the cities of the Medes. 18:12 This happened because they did not obey the LORD their God and broke his agreement with them. They did not pay attention to and obey all that Moses, the LORD’s servant, had commanded.
Sennacherib Invades Judah, 13-27
18:13 In the fourteenth year of King Hezekiah’s reign, King Sennacherib of Assyria marched up against all the fortified cities of Judah and captured them. 18:14 King Hezekiah of Judah sent this message to the king of Assyria, who was at Lachish, “I have violated our treaty. If you leave, I will do whatever you demand.” So the king of Assyria demanded that King Hezekiah of Judah pay three hundred talents of silver and thirty talents of gold. 18:15 Hezekiah gave him all the silver in the LORD’s temple and in the treasuries of the royal palace. 18:16 At that time King Hezekiah of Judah stripped the metal overlays from the doors of the LORD’s temple and from the posts which he had plated and gave them to the king of Assyria.
Olley points to the narrative conflict here:
‘How can Hezekiah’s standard apology to Sennacherib, backed by tribute (vv14-15), be reconciled with the introduction that makes Hezekiah’s rebellion evidence of “success” because “the Lord was with him”?’
18:17 The king of Assyria sent his commanding general, the chief eunuch, and the chief adviser from Lachish to King Hezekiah in Jerusalem, along with a large army. They went up and arrived at Jerusalem. They went and stood at the conduit of the upper pool which is located on the road to the field where they wash and dry cloth. 18:18 They summoned the king, so Eliakim son of Hilkiah, the palace supervisor, accompanied by Shebna the scribe and Joah son of Asaph, the secretary, went out to meet them.
Hezekiah’s attempts at appeasement have not worked. Sennacherib boasted:
‘As to Hezekiah, the Judean…he himself, I locked up within Jerusalem, his royal city, like a bird in a cage. I surrounded him with earthworks, and made it unthinkable for him to exit by the city gate.’ (Cited by Olley)
18:19 The chief adviser said to them, “Tell Hezekiah: ‘This is what the great king, the king of Assyria, says: “What is your source of confidence? 18:20 Your claim to have a strategy and military strength is just empty talk. In whom are you trusting that you would dare to rebel against me? 18:21 Now look, you must be trusting in Egypt, that splintered reed staff. If a man leans for support on it, it punctures his hand and wounds him. That is what Pharaoh king of Egypt does to all who trust in him. 18:22 Perhaps you will tell me, ‘We are trusting in the LORD our God.’ But Hezekiah is the one who eliminated his high places and altars and then told the people of Judah and Jerusalem, ‘You must worship at this altar in Jerusalem.’ 18:23 Now make a deal with my master the king of Assyria, and I will give you two thousand horses, provided you can find enough riders for them. 18:24 Certainly you will not refuse one of my master’s minor officials and trust in Egypt for chariots and horsemen. 18:25 Furthermore it was by the command of the LORD that I marched up against this place to destroy it. The LORD told me, ‘March up against this land and destroy it.’ ” ’ ”
‘In the field commander’s speech, perceptions of relative power and status are clear. Hezekiah is referred to by name, but never as “king” (vv22,29-32), while Sennacherib is never named but is “the great king” (vv19,28) or “the king of Assyria” (vv 19,23,28,30, 31,33) – in contrast the writer’s own words are “King Hezekiah” (v17; 19:1,5).’ (Olley)
18:26 Eliakim son of Hilkiah, Shebna, and Joah said to the chief adviser, “Speak to your servants in Aramaic, for we understand it. Don’t speak with us in the Judahite dialect in the hearing of the people who are on the wall.” 18:27 But the chief adviser said to them, “My master did not send me to speak these words only to your master and to you. His message is also for the men who sit on the wall, for they will eat their own excrement and drink their own urine along with you.”
18:28 The chief adviser then stood there and called out loudly in the Judahite dialect, “Listen to the message of the great king, the king of Assyria. 18:29 This is what the king says: ‘Don’t let Hezekiah mislead you, for he is not able to rescue you from my hand! 18:30 Don’t let Hezekiah talk you into trusting in the LORD when he says, “The LORD will certainly rescue us; this city will not be handed over to the king of Assyria.” 18:31 Don’t listen to Hezekiah!’ For this is what the king of Assyria says, ‘Send me a token of your submission and surrender to me. Then each of you may eat from his own vine and fig tree and drink water from his own cistern, 18:32 until I come and take you to a land just like your own—a land of grain and new wine, a land of bread and vineyards, a land of olive trees and honey. Then you will live and not die. Don’t listen to Hezekiah, for he is misleading you when he says, “The LORD will rescue us.” 18:33 Have any of the gods of the nations actually rescued his land from the power of the king of Assyria? 18:34 Where are the gods of Hamath and Arpad? Where are the gods of Sepharvaim, Hena, and Ivvah? Indeed, did any gods rescue Samaria from my power? 18:35 Who among all the gods of the lands has rescued their lands from my power? So how can the LORD rescue Jerusalem from my power?’ ” 18:36 The people were silent and did not respond, for the king had ordered, “Don’t respond to him.”
“Then you will live and not die” – ‘Sennacherib offers the people “life”, in another land, as opposed to “death”, in their own’ (Olley). This is a precisd reversal of Deut 30:15-20, where the alternatives are blessing in the land God has given his people (“life”), or destruction and removal from the land (“death”).
“How can the LORD rescue Jerusalem from my power?” – And so the real battle lines are made clear: it is not Sennacherib against Assyria, but Sennacherib against the Lord. (Olley)
The message is powerfully deceptive. How many of us, today, in our work, politics, or business dealings, conclude that the only way to succeed in life is to conform to the attitudes and practices of the world? How often do we think and behave as if faith in God was irrelevant – an uncumbrance, even? But, when we find the courage to stand against the world’s might, we are standing with our Saviour, who, when brought before Pilate, did not flinch. (See Olley, p324f)