It is 1910 and a warehouse fire on the banks of the Thames has left one criminal dead and another charged with his murder. Convinced of his innocence, Jessie Beale begs barrister Daniel Pitt to defend the accused. It's a hopeless case - unless Daniel can find an expert witness, whose testimony on fire damage is so utterly convincing that any jury would believe him. Daniel's friend Miriam fford Croft was taught by formidable forensic scientist Sir Barnabas Saltram, who has built his reputation on giving evidence of this kind. But when Saltram agrees to testify, thus saving an innocent man from the gallows, Daniel unwittingly starts a chain of events that has devastating consequences for all of them.