Aren't You Guy Haines?

[deckardcanine]

A tennis champ named Guy encounters someone on a train,
Named Bruno, who is devious and not entirely sane.
The latter knows the former wants to leave his cheating wife,
But Miriam’s decided to remain with him for life,
So Bruno has a plan: He knocks off Miriam for Guy,
And Guy kills Bruno’s dad. The cops would see no reason why,
So neither of the murderers should even be suspected,
With alibis for deaths of those more blatantly connected.
Guy nervously pretends the scheme amuses him and leaves.
That constitutes a bargain sealed as Bruno misperceives.
Soon Miriam is dead, and Bruno turns the screws on Guy
To take his turn as hit man. Will our hero thus comply?
If not, he risks a frame-up job that’s simple yet compelling.
You’d better learn the ending for yourself, as I’m not telling.