The one where Barbara is captured by a gang of wasps...
We rejoin our heroes' adventure on this most alien of alien worlds with the triple threat from the previous cliffhanger - the TARDIS (with Vicki inside) has been stolen, Ian has been caught up in a strange webby trap, and Barbara is walking headlong into a pool of acid. It's real comic strip fantasy adventure of the Terry Nation school of writing. Let's follow each threat in turn to its conclusion...
First up, the hypnotised Barbara. She narrowly avoids stepping into the acid pool thanks to a burbly signal from a stray Zarbi, but she soon finds her way into the lair of another race of creatures, the Menoptera. There's a startling shot when Barbara's wandering aimlessly toward the camera, and just as she walks past, a Menoptera jumps up right in front of the screen in possibly Doctor Who's first ever jump scare. It's a truly arresting sight because it's totally unexpected and then when you see what it is, your brain runs hard to catch up and process what you're seeing. The Menoptera are magnificently strange creatures, and although not quite as effective or convincing as the Zarbi, are beautifully designed by Daphne Dare. As with the Zarbi, they look precisely how you'd expect a giant wasp to look, but unfortunately a little comical with it (their sad expressions and big black eyes).