Summary Tales of a monster haunting Loch Ness go back for nearly 1,500 years, but only in the last century did the legend truly take off. Since the 1930s, over 1,000 eye witnesses have used mysterious photographs, eerie videos and unexplained sonar readings to back up their accounts of seeing the beast. The evidence is always tantalising but never definitive. At St Andrews University, Dr Charles Paxton, an expert on large marine creatures, has now compiled a unique database of every sighting of the creature ever reported. His team hope through detailed analysis of this astonishing database to finally explain the truth behind the myth of the Loch Ness monster. The programme looks at how hopes of finding a surviving dinosaur were dashed by a hoax that fooled everyone. In a sophisticated laboratory, staff explain the science behind the sightings of multiple-humped monsters on Loch Ness. Elsewhere, fabled Nessie hunter Adrian Shine recounts his decades-long search for the elusive beast. Historian Albert Jack believes that the mystery was kick-started by the sight of bathing circus elephants, which could account for reports of humped bodies, dark wrinkled skin and eel-like trunks. This intriguing theory fails to account for all the sightings, however, and psychologist Chris French believes that he has the answer. Using Dr Paxton's unique database, French reveals that the peaks and troughs in sightings over the last century coincide perfectly with dramatic events in popular culture. The real source of the Loch Ness monster, he posits, lies in the complex interaction between media reports of hoaxes, natural phenomena and everyday animals and our own monstrous imaginations.

• Documentary