Business Unusual by Gary Russell

A security force without any identity... an MD with no name... a sinister and hellish creature on guard patrol, you could say that SenéNet is no ordinary multinational company.

The Doctor, travelling alone, arrives in Brighton, 1989 and soon discovers his old friend, the Brigadier, has gone missing. The Brigadier was last seen investigating SenéNet at their headquarters, whose new interactive games console is soon to be released at an absurdly reasonable price.

Investigating further, the Doctor becomes more and more entangled in a deadly web of intrigue. Together with a plucky computer programmer from Pease Pottage called Mel, the Doctor must overcome the conspiracy of silence, rescue the Brigadier and save the world once again - something that would be a lot easier if he just knew where to start...