First broadcast 3rd/4th February 2020.<br /><br />Thomas investigates the case of John Sealy, a soldier who died during a military training exercise involving exposure to CS gas.<br /><br />Will Stevens - Pvt. John Sealy<br />Daniel Stewart - Sgt. Haring<br />William Ash - Major Mark Sealy<br />Clare Higgins - Professor Katherine Dukes<br />Richard Lintern - Dr. Thomas Chamberlain<br />Ben Bailey Smith - Lt. Col. Ben Carmichael<br />Robert East - Henry Young<br />Ash Tandon - DI Karl Guyatt<br />Dan Parr - Edmund 'Fish' Fishbourne<br />Richard Durden - Conor Hodgson<br />David Caves - Jack Hodgson<br />Emilia Fox - Dr. Nikki Alexander<br />Adelle Leonce - DS Lucy Vail<br />Graham Turner - Arthur Simpson<br />Tina Chiang - Simone Taylor<br />Julia Haworth - Rosie Chamberlain<br />Liz Carr - Clarissa Mullery<br />Daniel Weyman - Max Thorndyke<br />Elizabeth Boag - Paramedic<br />Michael Simkins - AC Harry Lennox<br />Caroline Lee-Johnson - Sandra Gibbs (as Caroline Lee Johnson)<br />Laura Lake - Book lover<br />Dan Parr - Fish
