A former Marines first day at Walmart is turned upside down when eco-terrorist capture the store and take his sister hostage.

I like how this logline has been worked - a former marine with PTSD who has to go back into action - great internal conflict, good stuff.

I like the critique of my logline. good job :)

The character flaw is welcome. We can keep it short by switching to the "PTSD" acronym -- it's common enough, right? And we can do some "2+2" instead of stating outright he was discharged for PTSD. We're told he's an "ex" marine, so we can connect the dots with:

"On his first day at Walmart, a ex-marine with PTSD must save his sister when eco-terrorists seize the store and take hostages.

Adding the PTSD gives us a clearer idea how this story might play out, and it directly opposes his outer goal. Nice work.