The tale of Crusader, the jet-powered boat of 1952, appears to be a simple one about the ambition of John Cobb and Reid Railton, two unassuming but deeply gifted men, to break the water speed record on Loch Ness only for their efforts to end in tragedy. In fact the story behind that fateful outcome — Cobb's death on his first high-speed run — is a complex web of clever design and inspirational endeavour mixed with personality clashes and errors of judgment. After many years of research, including access to a wealth of original documentation, Steve Holter unravels the entire saga of the ill-fated Crusader and presents a compelling detective story. •John Cobb: the modest businessman with such a thirst for speed that he wanted to become the fastest man on water as well as on wheels after setting his land speed record of 396.196mph in 1947.•Reid Railton: inspired designer and long-time friend behind Cobb's greatest speed accomplishments, notably with the Napier-Railton (holder of the lap record at Brooklands) and the Railton Mobil Special (land speed record car).•In-depth study of Railton's innovative 'three-point' hull design for Crusader, with two rear sponsons and a single 'planing shoe' at the front — plus a De Havilland Ghost jet engine delivering 5,000lb of thrust.•Evolution of the design in parallel with testing of scale models, including a miniature jet-powered version evaluated near Portsmouth Harbour.•Assessment and description of boat-builder Vosper's wooden construction, under Peter Du Cane's direction.•An exhaustive account of proceedings at Loch Ness, where Cobb finally attempted a high-speed run on 29 September 1952 and achieved 206.89mph, faster than anyone had previously gone on water.•Analysis of the structural failure that destroyed Crusader and killed Cobb.Much of the story is told in the words of the key protagonists, drawing in particular on correspondence and written accounts from the key people involved, most notably John Cobb, Reid Railton and Peter Du Cane.