Claude Lacombe (François Truffaut)’s Timeline and Summary

Lacombe visits the Sonoran Desert, Mexico, and meets his translator and soon-to-be companion, David Laughlin. There, the research team discovers the missing Flight 19.
Some time later, Lacombe's research team travels to the Gobi Desert to find the missing Cotopaxi.
Ever the globetrotter, he next visits India to investigate a group of men reverently chanting a mysterious five-note phrase. When he asks where they heard the phrase, all of the men point to the sky.
Lacombe presents the five-tone phrase to UN delegates, stating he believes it's important.
He joins the researchers transmitting the five-tone phrase into space.
Later, Roy and Jillian are captured by the government in the evacuation zone. Lacombe questions Roy about his experiences.
Lacombe tries to convince Major Walsh that Roy and the others represent a cosmic sociological event, but Major Walsh has none of it.
When Lacombe sees Roy, Jillian and Larry escaping the helicopter, he chooses to say nothing.
During first contact, he directs the initial encounter like a composer. Pulling some strings, he also secures Roy a spot on Project Mayflower.
When the final alien emerges from the mother ship, Lacombe greets it with the hand signs for the five-tone phrase. The alien copies the gesture and the two share an understanding smile.