Her Alibi (1989)

Plot:

A writer of BAD detective novels is in full writers' block. He pretends to be the alibi of a beautiful woman who was arrested for murder at first thinking her innocent, but as she shows more and more interesting abilities (such as knife throwing) he begins to doubt his first assessment. He is still falling for her, but more and more nervous as time passes, and there are more close calls with death on his part.