The one where an aeroplane full of passengers disappears in an instant...
We pick this slow-moving but suitably intriguing tale up with the Doctor being frozen to death by icy gas jets in the Chameleon Tours hangar. Almost immediately, the Doctor hunkers into his coat, collar up around his ears, but it would be much simpler to move as far away from the icy jets as possible, rather than just flop down beside them. Still, at least the Doctor manages to outwit thicko Spencer with his own gas pen, and escape. It's funny, but during the brief moment where Troughton is in his shirt sleeves, he looks remarkably like he would in The Two Doctors, 18 years hence!
I said thicko Spencer because he just is. He's very straight and humourless (as all the Chameleons are) but he's also appallingly rubbish at any job he's given. Captain Blade really has got a liability on his hands (or "a fool" as Doctor Who villains prefer). Later on Spencer tries yet again to kill the Doctor, this time by getting bumbling Meadows to attach a destructive device to him. He's so desperate to have the Doctor dead, why doesn't he use a ray gun, or a gas pen? Why all these extravagantly silly methods of dispatch?