When a Mafia leader goes to jail, his impulsive shopaholic housewife must assume the role of mafia boss and finish his last deadly mission without jeopardize the rest of the family.

Thanks...
It's very helpful this.

Something like this?
'When a shopaholic mafia wife's husband goes to jail, she must assume the role of mafia boss and take down his arch rival to protect her family'

I enjoyed seeing the development of this logline through your comments, twilight. The only logline element that is unclear to me in your most recent update is what is at risk if she fails.

A possible revision:

When a shopaholic mafia wife's husband goes to jail, she must take down his arch rival to protect her family.

When a shopaholic mafia wife's husband goes to jail she must assume the role of mafia boss and finish a deadly mission, to taking down his arch rival.?