Take a dollop of Day of the Triffids, mix with a helping of The Thing and add a dash of The Avengers - result? The Seeds Of Doom of course! The opening 2 episodes remind me greatly of John Carpenter's 1982 version of The Thing despite the fact that this pre-dates it by some 6 years. This is yet another classic from the programme's golden age, and one of the scariest and most violent. The opening segment is a wonderfully claustrophobic fright-fest, with something very nasty lurking in the arctic wastes and a good dose of body horror. From part 3 onwards things move to the grounds of Harrison Chase's mansion and are equally tense and gripping with great use being made of the location and a marvellously eerie and atmospheric music score. Chase is a superb villain, totally unhinged and Scorby is an excellent henchman. Keeler's gradual transformation is wonderfully disturbing, in fact the whole story is full of disturbing moments (the meat grinder being particularly memorable). Tom is at possibly his most violent ever, brandishing a gun, smashing a chair over the bad guys, punching someone unconcious and twisting Scorby's neck painfully. Amelia Ducat is splendidly dotty and Lis Sladen is at her absolute best, standing up to the nasty Scorby and Chase with gusto.
The only disappointment is the ending with the Krynoid being bombed - it just seems to easy a resolution.
However, The Seeds of Doom is another gothic horror masterpeice.