This episode has been done much earlier in the series and is almost identical in the way it is played out. Darrin is convinced that Samantha is using witchcraft to help with an important advertising campaign and he simply won't believe that she did not do so. Darrin's masculine pride is hurt, of course, and he is not listening to reason on any level.
As in the highly similar previous episode, Samantha has to convince Darrin that he is barking up the wrong tree.
I found this one dull and repetitive.