The Strange Encounter (L'Étrange Rendez-Vous in the original French) is the fifteenth book in the Blake and Mortimer series created by Edgar P. Jacobs.
Kaufman's research indicates that it is the body of Scottish Major Lachlan Macquarrie who disappeared under strange circumstances after the British defeat at the Battles of Saratoga in 1777.
According to drummer boy Dermot Pitt, Macquarrie vanished late at night while investigating the sudden appearance of beams of light coming from out of the sky.
He also had in his possession some strange items including some glasses which enable the wearer to see clearly in the dark and a weapon which, when aimed at the head, causes the victim to fall asleep.
Wanting to examine the weapon more closely, Mortimer takes it with him before leaving the SUFOS offices, but, overcome with natural fatigue, returns it to Kaufman before booking into a hotel.
Mortimer tries to hitch-hike back to town only to come across two men wearing the same dark glasses as the first alien and knocking him out with the ray from a similar weapon.
Doctor Z'ong explains to Mortimer that he and his fellow "aliens" are in fact from the year 8061 (which was noted on Macquarrie's baldric), a time when the earth is just one dry desert with mankind on the verge of extinction.
Basam Damdu seemed the ideal choice to lead them and was picked up by the beams of light just before his capital was destroyed by the Swordfish aircraft designed by Mortimer.
Olrik then interrupts Z'ong and takes Mortimer outside the pumping station to a lake where his hands and legs are tied to a heavy weight and he is thrown into the water by the Asian soldiers.
They take him to a nearby underwater cave and turn out to be FBI agents led by John Calloway, head of its "Action" service, and Jessie Wingo, a Native American woman who knows the area well.
Evidence left behind shows signs of a sudden departure which means that Olrik and Z'ong are about to carry out their plan, which was dubbed Operation Poplar Trees, a word included on Macquarrie's baldric.
The shoulder strap had the words: "Yellow King, 8061, Danger, Light, Plutonian, H, Poplar Trees, Temple 1954" which translate into: Basam Damdu, the year of origin of the invaders, the threat, the lights used for time travel, the plutonium that is part of the H-bombs, Operation Poplar Trees and a comet discovered by Wilhelm Tempel which is due to appear on the 17 October 1954 in just a few days time and will be used to get the bombs into the future.
They discreetly take over the hills surrounding a plain in the desert from where they can see Olrik, his Asian troops and the men from the future preparing to ambush the convoy.
Major Lachlan Macquarrie, re-instated into the British army, is posthumously awarded the Victoria Cross for exceptional bravery and buried with honour.
Present at the funeral are Blake and Mortimer, who are then approached by the Cabinet Secretary, who informs them that a secret report on their adventure has been passed on to all of the world's heads of government, regardless of political ideology.