Trainee CONTROL agent requested by Maxwell Smart to assist in the mission to track down ex-KAOS agent and ACB founder Kubacheck. Max reasons that, as he is "a little rusty in his Mandarin Chinese", he may need Wu Fong's help if he has to chase Kubacheck into the Orient.
Unfortunately, Wu Fong is unavailable, reportedly having come down with a case of American flu.
This report comes from fellow trainee Samuels, who replaces him. However, since Samuels turns out to be Kubacheck - the very man they are looking for - it is more than likely that he has done away with Wu Fong.
[Mentioned, Episode #85: "Die, Spy".]