Chukas Summary

G-d commands the Children of Israel about the laws of the Red Heifer. It must be completely red without any blemish, and never have been placed in a yoke. It shall be slaughtered outside of the sanctuary, and some of its blood sprinkled in the direction of the Sanctuary. It shall then be entirely burnt, and cedar wood, hyssop and crimson thread thrown into the fire. The Kohen who performs this ceremony becomes tamei (ritually impure). The ashes should be gathered and placed outside the camp for safekeeping. The person who gathers the ashes also becomes tamei. Anyone who comes into contact with a corpse becomes Tamei, and must purify themselves by being sprinkled with water containing the ashes of the Red Heifer on the third and seventh day of the purification process. The person who sprinkles the ashes becomes tamei. Anyone who enters the Temple without undergoing this purification process will receive karet (be spiritually cut off). If there is a dead body in a room, any person or thing that is in that room, or enters into it becomes tamei, and requires purification with the ashes of the Red Heifer.
In the fortieth year in the desert, in the first month, the Children of Israel arrived at Kadesh in the Wilderness of Zin. Miriam dies and is buried there. There is no water for the people to drink, and they gather against Moshe and Aharon, complaining that they are about to perish. G-d instructs Moshe to take his staff and speak to the rock in the presence of the entire congregation. Moshe and Aharon gather the congregation, but instead of speaking to the rock, Moshe hits it twice. Water comes gushing out, but G-d punishes Moshe and Aharon for disobeying Him. Because they didn't sanctify G-d in the eyes of the nation, they will not be able to bring the Jews into the Land of Israel.
Moshe sends emissaries to the king of Edom asking permission to pass through their land. The king of Edom refuses and threatens war against the Jews.
The Jews arrive at Mount Hor. G-d instructs Moshe to lead Aharon and Elazar his son up the mountain. Moshe dresses Elazar in Aharon's priestly robes, and Aharon dies there. The entire nation mourns Aharon's death for 30 days. The Canaanite king of Arad wages war against Israel and takes a captive. Israel vows that if G-d will help them to defeat the Canaanites they will consecrate all the spoils of victory to G-d. G-d hears the prayer of the people, and delivers the Canaanites into their hands.
The people journey on, and once again complain that they have no substantial food or water. G-d sends serpents to attack the people. and a large multitude die. The people come to Moshe, admit their sin and ask Moshe to pray for them. G-d instructs Moshe to make a serpent and place it on a pole. Anyone who is bitten should look at the serpent and they will live. Moshe makes the serpent (Nachash) out of copper (Nechoshet).
The Torah lists the journeys of the Children of Israel.
After passing through valley of the river of Arnon the Children of Israel sing a song of thanksgiving to G-d for the miracles which he performed to them there. (The Torah doesn't explain the miracles, but we have a tradition that He miraculously killed the Emorites who were waiting there in ambush for the Jews.)
The Jews ask permission to pass through the land of Sichon, king of the Emorites. He refuses and wages war on them. They defeat Sichon and take possession of his land. Israel settles in the land of the Emorites and Moshe sends spies to Yazer. They conquer its suburbs, and drive away the Emorites remaining there. They then turn toward Bashan. Og, the king, comes out to fight them and he and his people are totally destroyed. The Children of Israel take possession of his land. They then journey and encamp on the plains of Moav on the bank of the Jordan opposite Jericho.