Red Shoe Diaries S03 E01 In the Blink of an Eye

"Trapped by a burning secret. Torn by a blazing desire."

Kathryn's a horse trainer who's happily married to Kirk, a boxing trainer. When Rob, one of Kirk's virile boxers, enters Kathryn's stable her heart starts to trot. When Kirk discovers their tryst, he's set to deliver his own knockout blow.