After an accident a young boy begins to hear his cat talking to him – telling him to kill.

Agreed with dpg

Also he can easily overpower a cat!
If the going gets tough, he can always throw it down the chute

The premise of a talking tom is interesting though...

And then what?

The logline sets up a situation for a plot but it needs to follow through with a concise statement of a complete plot.

What does he do about the cat's voice?? What becomes his objective goal, for better or worse?