Black Widow - Part 1

First of a two-part special taking viewers behind the scenes of a Cambridgeshire police investigation into a woman who is plotting to have her ex-husband killed. A man handed police a secretly recorded conversation that appeared to show his girlfriend offering to pay someone to commit murder, and DS Mike Barnshaw has to work out whether the recording is evidence that she really wanted him dead or is pillow talk with a man she has picked up on a dating site.