When a deadly soil-borne virus is released in Canberra, an obsessed scientist battles military and political forces to save the city from pre-emptive destruction.

Just caught up with this again. I'm Australian hence the Canberra bashing - no offense intended. Your latest is way better. Still question the need to specify "soil borne" unless you need to signal a slowed-down process (and maybe "a creeping virus" would better describe your situation. If Canberra is a must then "capital city" makes it clearer and raises the stakes.

Good luck with it.

Your last draft of the logline reads very well and has all the story elements a logline needs. I would change "when" to After as the MC would likely take action only after the inciting incident.

I take it from your last post that you are either pitching or submitting this so good luck.

Food for thought. The 25 word limit is mandatory in this case. So let's try this:

"When a deadly soil-borne virus escapes from a laboratory, a discredited scientist battles to save the city from being nuked by the military."