Fritz was a Nazi expeditioneer that travelled to the mopu lamasery in search of Shamba-La However, when John arrived it was agreed that he would bring them back to Berlin. Like the other soldiers, he had been trapped in time for many years and still thinks it is 1938.
He was friendly to John and even talked to him about his brother and dog, which he compared to Mr. Rakshasas. He compliment him that he spoke fluent German, which John had given homself the ablility to in The Blue Djinn of Babylon.
He gave him a pocketknife in case he needed to cut the ropes he were tied to. John reminded Fritz of his son, who he hoped someone would do the same for him.