Haney, Dillin and Cuidera conclude the story of the android agent, Johnny Vak, in Blackhawk 238 (Dec/Jan 67/68).
Following their discovery at the end of the previous issue that Johnny Vak was working with Barbarossa, the Blackhawks are taken captive, and learn that Barbarossa is behind the deaths of other GEORGE operatives. The team gets knocked out, and then wake up, free.
They all have splitting headaches, and when they return to GEORGE headquarters, they learn from Mr. Delta that Barbarossa has planted bombs in their brains. Seriously, the only thing I really like about this story is the panel of the bird-plane. Anyway, Mr. Delta throws the team back into the brig, and once again they escape. Probably should have expected that, as it happened in the last issue as well.
The team confront Barbarossa a second time, and send him falling to his death.
As the issue ends, Mr. Delta reveals that he knew Barbarossa had reprogrammed Johnny Vak, but allowed that to continue. He had his own secret operative inside Barbarossa ranks, who implanted phony bombs, not real ones, in their brains.
So pretty much this entire story has consisted of Mr. Delta lying to the Blackhawks and manipulating them, making everything far more dangerous and complicated than it needed to be, for no logical reason.