The novelistation of 'The Ark' was written by Paul Erickson.
Back Cover Blurb
'If this is Earth, the it's no longer inhabited by human life!'
It is ten million years in the future and the Earth is about to plunge into the Sun. A gigantic Space ARk has been launched to take the last of humanity to a new life on the planet Refusis. Accompanying the humans on the journey are the Monoids, strange reptilian creatures from an alien world.
When the TARDIS materializes on board, the Doctor and his friends are greeted with suspicion which soon turns to open hostility when Dodo inadvertently infects the Ark's crew with a long-forgotten virus.
It is and accident which will have a terrible effect on mankind, an effect which will last for seven hundred years...