Adam tries to understand how a murder conviction can be beyond reasonable doubt – when there is no body. John McKenna may have been convicted of murdering his common-law wife, but her body has never been found. Meanwhile, Ford makes Nick struggle with a case that is over 300 years old – an attempt to prove the innocence of a woman who was executed as a witch.Sarah is caught off-guard when her boyfriend from home, Craig, turns up with an unexpected proposal.