Heartbeat (1992)

S15E10 Burden of Proof

Blaketon witnesses Arthur Bolton, a local coal merchant, kissing another woman and promptly informs his wife about the betrayal. The following day, Arthur is discovered murdered, making Blaketon the main suspect. This forces PC Walker to take charge of the investigation to exonerate his friend. Meanwhile, Peggy's luck takes a turn when the greyhound she purchases turns out to be a dud, failing to compete at all.