Doctor Who (1963–1989)
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The Power of Kroll: Part One 

The TARDIS arrives at it's next destination, the marsh planet "Delta Magna". Where the Doctor and Romana goes in search of the fifth segment to the Key to Time. Where they discover the ... See full summary »


Norman Stewart


Robert Holmes (by)




Episode complete credited cast:
Tom Baker ... Doctor Who
Mary Tamm ... Romana
Neil McCarthy ... Thawn
John Abineri ... Ranquin
Philip Madoc ... Fenner
Glyn Owen Glyn Owen ... Rohm-Dutt
Carl Rigg ... Varlik
Frank Jarvis Frank Jarvis ... Skart
John Leeson ... Dugeen
Grahame Mallard Grahame Mallard ... Harg
Terry Walsh ... Mensch


The TARDIS arrives at it's next destination, the marsh planet "Delta Magna". Where the Doctor and Romana goes in search of the fifth segment to the Key to Time. Where they discover the native tribal Swampies worships Kroll, a gigantic squid as a god, only to find Kroll has accidentally swallowed the fifth segment and Romana is chosen by the Swampies for sacrifice and The Doctor sets out to save a local refinery from being attacked by Kroll. Written by Daniel Williamson

Plot Summary | Add Synopsis


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Release Date:

23 December 1978 (UK) See more »

Company Credits

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Technical Specs


Sound Mix:




Aspect Ratio:

1.33 : 1
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Did You Know?


The episodes of this serial are noticeably shorter than average. While it was normal at the time for individual episodes to fluctuate between twenty-three and twenty-five minute, the episodes of this serial clocked in as little as just over twenty-one minutes. The final running time for the whole serial is 90 minutes, as is noted by the DVD of this story. See more »


After landing in the TARDIS, the Doctor and Romana become separated when Romana climbs a hill to get a better reading with the tracer for the Key to Time. She's kidnapped by the local swamp tribe, and a bit later the Doctor is taken by workers from a methane refinery. While they are apprehending him, the tracer can clearly be seen sticking out of his coat pocket, even though Romana would have had no chance to give it back to him. See more »


Romana: Oh, it's a sort of Holy Writ?
The Doctor: It's atrociously writ.
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Badinerie: Orchestral Suite No. 2 in B Minor, BWV 1067
Composed by Johann Sebastian Bach
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User Reviews

Kroll Criticism
18 January 2020 | by A_Kind_Of_CineMagicSee all my reviews

Review for all 4 parts:

I think this is a very underrated story. It is nothing special and pales in comparison to the greatest serials but it is a perfectly decent, standard adventure in my opinion rather than the weak disappointment that others seem to see it as.

The storyline of The Doctor and Romana searching for the next segment of the key to time on a planet being exploited by outsiders for its resources and encountering an uprising from the natives as well as a giant swamp monster is a pretty run of the mill setting for a filler story but is a reasonable enough plot. The thing that lifts it for me is the writing from the great Robert Holmes. It is nowhere near his best work but it has good dialogue, some thoughtful themes, some believable writing of characters and some smart humour. The acting of the 'swampie' natives is nothing impressive but not awful and their poor visual creation with green make up and dreadlock wigs is really the only issue that really stands out as silly. I think that given the restrictions of the age and budget that is forgivable. If you replaced the swampies with effectively created alien natives it would eliminate that issue so is it really a major problem? I feel the writing is strong enough and the acting decent enough to gloss over the visual shortcomings. The swamp beast looks poor by the standards of the best technology of the time or by modern possibilities but I feel it was a decent effort for the age this was made and it is a fun creation with some enjoyable scenes of its attacks.

There is an ecological underlying theme of exploiting resources and lack of regard for nature or indigenous people as well as another element of superstition versus science. I really enjoy the ideas and dialogue. I also enjoy the political clash of the human characters who are well acted with the wonderful Phillip Madoc especially convincing.

Tom Baker and Mary Tamm are as effervescent as ever as The Doctor and Romana and while the story is no classic it is a solid serial in my opinion. I am a bit sad that it gets a lot of criticism.

My ratings: Parts 1 & 2 - 8/10, Part 3 - 7.5/10, Part 4 - 8.5/10. Overall - 8/10.

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