In Sergeant Bigglesworth C.I.D., Max Grindler is a member of a gang of airborne bandits led by Julius Hans Gontermann.
Grindler was formerly a gangster in America where he had, at one time, been known as "The Pike" and had been labeled "Public Enemy No. 1". When he was arrested, his associate Gontermann betrayed him, turned states evidence and got off with a light sentence.
Subsequently, Gontermann had been deported to Germany where he joined the Nazi party and attained a senior rank. After the war, Gontermann had gone into hiding. Meanwhile Grindler had spent most of the war in New York State Penitentiary. Some two months before the events in the book, Grindler escaped and made his way to Europe to hunt down Gontermann. Gontermann must have somehow turned the tables and persuaded Grindler to join his gang of airborne pirates instead. Using fast aircraft with a long-range, they could commit spectacular robberies of high value targets and be far away before the authorities arrived. Grindler, it seemed, agreed.
Although Grindler was not a pilot, it can be assumed that he brought some other valuable skill to the gang. He might have been the one who, for example, cut open the safe of the Rajah, allowing the gang to get away with almost half-a-million pounds worth of pearls.
Grindler was the hot-headed member of the team, as befited his image as an ex-American gangster. He prefered shooting to talking and was in favour of killing Biggles straight away when he was captured by the gang at El Zufra.
Towards the end of the book, he found himself betrayed once again by Gontermann during their escape from the authorities. Gontermann took off in his aircraft and abandoned Grindler at El Zufra. Even then he refused to give him. He had expended most of his ammunition shooting at Gontermann's escaping aircraft and had only one bullet left. Even so, rather than go quietly with Biggles, he declared that if he had to be marooned at the oasis, he would ensure that Biggles and Ginger remained with him. Saying thus, he ran towards Biggles' aircraft with the intention of disabling it but didn't get far. On the way, he leapt into a hollow and was killed by a massive explosion. It turned out that the mines which Sergeant Mahmud and his troops had cleared from the oasis had been piled in the hollow.
Grindler was described as forty-nine and of medium height and build, with black hair and grey eyes. His nose was slightly bent and the little finger from his left hand was missing.