A Shade Of Doubt - S4.E16

Gary Arnold and his daughter Su are forced to land in Coopers Crossing, Gary has collapsed over the controls. In hosptial nobody seems to know what's the matter with him. Finally Geoff has a hunch, he reckons it could be typhoid, and it is. Everybody is very upset, and they make sure to keep a distance to Su. Marty, who has taken Su under his wings, defend her. Finally it turned out Su came from a camp in Thailand, where she'd been ever since her mother died. Gary had tried to get her out of there, without success, so they had fled Thailand and entered Australia illegally. Jack worked it out though, and they could stay.