In case you didn't know already, this starts today:
Twenty-five years after the original radio series of Douglas Adams’ The Hitchhiker’s Guide To The Galaxy exploded into the public consciousness, the further exploits of its bewildered hero, Arthur Dent, are being brought to life in their original medium and with the (mainly) original cast.
The last three books of the ‘trilogy in five parts’, Life, The Universe And Everything; So Long And Thanks For All The Fish and Mostly Harmless, have been dramatised as two new series (none of them were previously produced for radio).
As the original two series were dubbed the Primary and Secondary Phases by Douglas Adams, these new series form the Tertiary, Quadrenary and Quintessential Phases.
Thanks to the wonders of digital technology, Douglas Adams himself can be heard playing the part of Agrajag.