The introduction to the Golden era of Doctor Who is another great place to start. The Ark In Space is the first space-bound adventure of Tom Baker's Fourth Doctor and the companion dream team that was Elizabeth Sladen's Sarah Jane and Ian Marter's Harry. It was also Russell T Davies' and Steven Moffat's favourite, so it's a good chance to see what inspired them in their own attempts to recreate Doctor Who for the 21st century. The TARDIS materialises on a ship filled with cryogenic-ally frozen humans, sleeping for hundreds of years after the Earth was devestated. Only an alien force is stalking the ship and the Doctor and Harry and Sarah must help the ship's inhabitants survive. It is a wonderfully tense story with plenty of mystery and a hint of Alien about it too. Sure the effects used to create the monstrous Wirrn aren't exactly brilliant, but it's still suitably creepy nonetheless. Tom Baker, in his second story, is as engaging as ever and Elizabeth Sladen shows what really makes a great companion. It is also the story that spring boards many fantastic stories to come. Welcome to the Hinchcliffe era of Doctor Who - whether you've only seen Nu Who or are just interested in the show in general, you are in for a treat.