SUSAN: Barbara, I’ve got an idea.

BARBARA: What?

SUSAN: He’s quiet now, but we can’t be sure the Sensorites won’t make him help them. Look, if they can use their brains, why can’t we use ours?

BARBARA: To defend him?

SUSAN: Yes, and ourselves. Grandfather and I landed on a planet once called Esto. The plants there used thought transference. If you stood in between two of the plants, they set up a sort of screeching noise. Grandfather said it was because they were aware of another mind.

BARBARA: Breaking in on their communications.

SUSAN: Yes, exactly. I thought if we both tried together.