Kayan had remained at Telapur with Ah Wong when the Japanese invaded the Malayan peninsula. Kayan had pleaded with the Japanese troops not to burn his house but had ended up being severely flogged. The Japanese had also killed his wife and children, leaving him with an enduring hatred of the invaders.
Some time later, Biggles arrived with Fee Wong, Ah Wong's brother, to attempt to sabotage a valuable Japanese convoy of rubber on the river which would be passing the saw mill. However they were stymied when they found the barges under guard at Telapur. The original plan to have Ah Wong's workmen cut the mooring ropes had to be abandoned. They were stuck without options until Biggles heard the sound of some of Ah Wong's elephants. Knowing that elephants were used for timber work, Biggles hatched a plan to use them to push Ah Wong's logs into the strong river currents where they would become battering rams against the convoy. Ah Wong had over a hundred elephants and, supervised by Kayan, this plan was soon put into effect. However a fallen tree had trapped some of the logs, creating a massive logjam. Without hesitation, Kayan jumped onto the logs with a heavy crowbar and freed the logs. He was last seen with "arms outstretched like a bronze statue in an attitude of triumph". Kayan was swept away by the resulting torrent of water and logs but his sacrifice led to the destruction of the convoy.