In the spring of 1742, not discouraged by the failure of the previous year, Pierre set out again for the Mandans, accompanied this time by his brother François, who was known as the Chevalier, and by two men from the fort. The journey was to prove momentous, but at first the outlook was dark. When they arrived in the Mandan country they could find no sign of the Horse Indians, as the mounted Indians from the West were called. Pierre and his brother waited long at the Mandan village with what patience they could summon. The month of May went by, then June, then most of July, with still no sign of the missing band. Finally the brothers decided that, if they were to go farther west, they could wait no longer, for the season was advancing and it would soon be too late to do anything. At last they found among the Mandans two young men who agreed to lead them to the country of the Horse People. This would bring them to their hoped-for guides. Without a moment's delay they set out towards the south-west in search of the missing Indians.

They travelled for twenty days in a south-westerly direction, through what were afterwards known as the Bad Lands of the Little Missouri, a country unlike anything they had ever seen before. On every side they could see mounds and pillars of brilliantly-coloured earth, blue and crimson and green and yellow. So much were they struck with the singular spectacle that they would have liked to carry some of the coloured earth with them to show to their father on their return. But a long journey lay before them. They had to carry everything they needed on their backs, and it would have been folly to add to the load something that was useless for their immediate needs, something that they could neither eat nor wear.

About the beginning of August the party reached a mountain where the Mandans expected to find the Horse Indians so eagerly sought. But the Horse Indians had gone on a hunting expedition and had not yet returned; so Pierre and his brother decided to wait for them. On the summit of the mountain they made a signal fire, and every day one of the explorers climbed up to the lookout to see if there were any signs of the Indians. At the foot of the mountain they built a small house in which they lived. Some of their time they spent in hunting to provision the camp, while waiting as patiently as they could for the Horse Indians to return from their hunting.

At last, on September 14, a smoke was seen rising in the south-western sky. One of the men was sent to investigate, and he found not the Horse Indians but a band known to the Mandans as the Good-looking Indians. Difficulties multiplied. One of the Mandan guides had already deserted them to go back to the Missouri, and the other now told the brothers that he must leave them. He was prompted by fear. The Good-looking Indians were not on friendly terms with the Mandans, and, although they had not offered to do him any harm, he was afraid to remain near these enemies.

After the Mandan had gone back, the brothers La Vérendrye managed to explain to the Good-looking Indians by signs that they were seeking the Horse Indians and asked for guides to one of the camps of these Indians. One of the Good-looking Indians said he knew the way, and they set out under his guidance; but they became anxious on finding that they were still travelling in the same direction as before, for this did not seem to be a very direct road to the Western Sea. Still, they had fixed their hopes on the Horse Indians as the people able to lead them there, and the most urgent thing to do was to find some members of that tribe, even though they had to go a long way out of their course to do so.

On the second day after they left the camp of the Good-looking Indians, they met a party of another tribe known as the Little Foxes, who were very friendly. The explorers gave them some small presents, and made them understand that they were seeking the Horse Indians, who had promised to show them the way to the sea. 'We will take you to the Horse Indians,' they said, and their whole party turned about and joined the French. But these new guides also, to the disgust of François La Vérendrye, still marched towards the south-west. 'I felt sure,' he said, 'that in this direction we should never find the Western Sea.' However, there was nothing to do but to go forward, and to trust to better luck after they reached the Horse Indians.

After tramping on for many days they came at last to an encampment of the Horse Indians. These people, just then, were in great trouble. They had been attacked not long before by a war party of the Snake Indians; many of their bravest warriors had been killed, and many of their women had been carried into captivity. When asked the way to the sea these Indians now declared that none of them had ever been there, for the very good reason that the country of the fierce Snake Indians must be crossed to reach it. They said that a neighbouring tribe, the Bow Indians, might be able to give some information, as they either themselves traded with the white men of the sea-coast, or were on friendly terms with other tribes who had been down to the sea. These Bow Indians, they added, were the only tribe who dared to fight against the Snake Indians, for they were under the leadership of a wise and skilful chief, who had more than once led his tribe to victory against these dangerous enemies. A guide was found to lead the explorers to the Bow Indians, and they went off once more, still travelling south-westerly, until at length, on November 21, they came in sight of the camp of the Bows. It was a huge camp, much larger than any the explorers had yet visited. Everywhere they could see numbers of horses, asses, and mules—animals unknown among the northern tribes.

When they reached the camp the chief of the Bows met them and at once took them to his own lodge. Nothing could be more friendly or polite than his treatment of the white travellers. In fact, as François said, he did not seem to have the manners of a savage. 'Up to that time we had always been very well received in the villages we had visited, but what we had before experienced in that way was nothing in comparison with the gracious manners of the head chief of the Bows. He took as much care of all our belongings as if they had been his own.' With him François and his brother remained for some time; and, very soon, through the kindness of the chief, they learnt enough of the language to make themselves understood.