It's London, 1828, and the father-and-son team of Marc and Isambard Kingdom Brunel are masterminding a dangerous project -the digging of the Thames Tunnel. There's just one problem... The Brunels' tunnel is haunted. Every night, a spectral blue lady walks the excavation. Now, the 22-year-old Isambard, eager to step out of his famous father's shadow, finds himself dealing with not only the supposed supernatural, but a second unexpected guest - a colourful trespasser who calls himself 'The Doctor'. Isambard would like to know a great deal more about this strange man and his mysterious blue box...Big Finish have been producing Doctor Who audios since 1999, starring Tom Baker, Peter Davison, Colin Baker, Sylvester McCoy, Paul McGann, David Tennant and John Hurt. The Doctor in this story is played by Colin Baker, familiar to many viewers and audiences not only as the Doctor, but also for his popular stay in I'm A Celebrity Get Me Out of Here! CAST: Colin Baker (The Doctor), James MacCallum (Isambard Kingdom Brunel), Christopher Fairbank (Marc Brunel), Catherine Bailey(Tan), Imogen Church (Rispa / Lady Raffles), Becky Wright (Flo Hawkins / Alayna), Anthony Townsend (Richard Beamish / John Chubb), Sam Woodward (Charlie / Lord Raffles / Captain Sanderson), Richard Unwin (Tour Guide / Scientist).