In the novel Destination Unknown, Dr Paul Van Heidam is one of the senior members of the management at Aristides's research establishment at a remote location in the High Atlas Mountains. His exact positiion is not stated but he functions as a sort of Chief of Staff or Director of Operations. When new arrivals turn up at the research station, he greets them and takes them around. When delegations of visitors come for inspections of the facility, he hosts the visitors on behalf of Mr Aristides and also gives them a conducted tour. Before the visit, he is in charge of ensuring all occupants of the station who should not be seen are herded into their secret "emergency quarters".
Van Heidem is Dutch and he is addressed as "doctor" but it is not clear what his academic specialty is and whether he engages in scientific or medical research.