When this four-part adventure first appeared in 1984, it was the only thing fans had to go on as their first impression of the new sixth Doctor (Colin Baker) until another season could be produced the next year. Baker gave it his all, drawing on his years as a character actor and frequent villain on British TV to play a manic, possibly schizophrenic, Time Lord immediately after regenerating, quoting Longfellow and nearly strangling his American assistant Peri (Nicola Bryant) at one point. The question was, would he ever settle down? Even by the last frame of this story, viewers couldn't be sure.

Thus, it's a shame such a heady performance couldn't have been engaged with a first-class script. Instead, writer Anthony Stevens, perhaps inspired by a recent garden infestation, pits the Doctor against the less-than-terrifying menace of giant slugs bent on conquering the universe using the computational powers of a pair of twin boys (hence the title). Even the Doctor must agree, saying, "In my time I have been threatened by experts. I don't rate you very highly at all." But through it all, Baker takes center stage, attempting to forge a bond with a skeptical audience (if not Peri) as the new Doctor who may not be as cuddly, warm, or even human, as previous incarnations. TV fixture Kevin McNally makes an early appearance as the young Lt. Hugo Lang, an aggressive space officer who takes his share of lumps during the story. --Ryan K. Johnson