One of the most amazing and gratifying things about the Big Finish Audio range is how good the sixth Doctor has become. Memories and videotape evidence suggests that his television stories were not that great. But in the sound only medium he is outstanding.

Arriving on the Galapagos Islands, the Doctor and Evelyn soon encounter a young Charles Darwin, who is on a journey of discovery aboard 'The Beagle' that will ensure his place in history. Providing mankind survives long enough for him to form his famous theories on evolution.

In the nearby town, Governor Lawson is sentencing locals to prison for little or no reason. A fisherman has seen 'devils' and deep beneath the Earth an ancient race is planning to take back Earth from the 'ape primitives' that currently inhabit the planet.

Its good to hear the Silurians make a long awaited return to Doctor Who. Bloodtide would have made a much better sequel to their original appearance than Warriors of the Deep. Even the Myrka gets a makeover this time around, sounding like a genuinely frightening creature rather than the pantomime horse we got on television. But then the special effects are always that much better on audio, aren't they?

Jonathan Morris, author of the much acclaimed fourth Doctor novel Festival of Death, turns in an excellent script, expertly directed by Gary Russell. I only have two small gripes about the production. One is that it gives a slightly different reason behind the Silurians hibernation. Theirs is an Earth undergoing huge climatic change. Would all that have been caused by the Moon entering orbit, the reason given in their original television debut? I don't know, as I'm not a scientific expert, but it doesn't detract from my enjoyment of the story.

The only other problem I have is that the regulars do tend to spend a lot of time during the middle episodes in one prison or another. But again, only a minor quibble.

Of the regulars, Colin Baker is in especially fine form. Such a shame that scripts of this quality were so rare during his brief spell on our screens. Big Finish has certainly given us the sixth Doctor as he should have been. And Maggie Stables continues to impress as Evelyn Smythe, more than a match for our favourite Time Lord.

The guest cast are very good too. Miles Richardson gives us a very uncertain Darwin, unsure whether his deductions and his faith in God can be reconciled. George Telfer is heroic as Captain Fitzroy, while Daniel Hogarth and Helen Goldwyn as Silurians Tulok and Sh'vak respectively are excellent in their roles.

Another winner from the Big Finish stable.