Rising out of the Solent, one mile off shore, like a silent sentinel, Spitbank Fort was constructed between 1861 and 1878 as one of Palmerston's Follies, a series of land and sea-based forts designed to repel French invaders during the Napoleonic Wars. Spitbank Fort was the last of four, fully armoured forts to be constructed to defend the Solent yet, ironically, by the time they were completed, the risk of invasion had passed. The forts were made ready for possible action during the first and second world wars, although they were never actually needed. Gradually, they fell into disrepair. Horse Sand Fort, was retained by the MOD but the remaining three - including Spitbank - were sold as private enterprises. The 19th century Spitbank Fort has just one recorded death, but this lonesome spirit is violent and unpredictable. Yvette Fielding and the team investigate ghostly phenomena in the Solent's chilly waters.