Karen and Sam could just be the perfect match. She is an extraordinarily demanding and sadistic dominatrix and he is biologically wired to take punishment delivered by a female hand no matter how severe and draconian Or at least he thinks he is.
Trouble is Sam is untested at the most extreme levels of service as, with his nervous approval, the woman he is now to address as Mistress Karen sets out to break and condition him into serving her. For only by dominating his mind, body, and spirit, can the dominatrix be sure that her chattel will be up to the task of enduring long periods in a chastity-cage from which only she can release him.
A genital confinement that will be the ultimate test of his submissive life thus far as the mistress of his dreams that he will undergo any deprivation in order to prove his worthiness to be owned and controlled completely beneath a female heel.