If you knock on enough doors, eventually one will open. Tireless investigators trace the infected blood from the arms of people with haemophilia back to the room where it all began – in that American prison. Read Cara’s notebook: www.telegraph.co.uk/notebook | For 30 days’ free access to The Telegraph: www.telegraph.co.uk/liespodcast | Get in touch: [email protected] and on Twitter @cjmcgoogan | See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.