Stefan Halper was a respected Cambridge University academic. But in autumn 2016 he was also something else - an FBI informant. Three Trump campaign figures targeted by Halper agree to talk. A story of subterfuge, secret recordings and the hazy morality of spying. 

Read more at www.telegraph.co.uk/crossfire |

Sign up to the US 2020 newsletter: http://telegraph.co.uk/podcast-us2020 |

Get 30 days’ free access to The Telegraph online: www.telegraph.co.uk/audio  |

Contact us: podcasts@telegraph.co.uk |

See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.