With the hope of regaining his former life, a prison councillor and functioning drug addict vows to help a psychologically damaged inmate deal with his past abuse as a subject in a 15 year drug trial.

I wonder in what way does “…the hope of regaining his former life…” influence the story?
Also not sure the reason for the inmate’s drug abuse (“…past abuse as a subject in a 15 year drug trial.”) should be in the logline. As long as he is a drug addicted or troubled inmate that needs help the MC will need to help him.

I don’t think this should be in the logline, if this is his motivation to pursue what it is he is pursuing, could you specify an event that happened to him that created this motivation? If so perhaps it would be better to write that into the logline instead of describing his motives.

The MC sounds very interesting the clearly contradicting characteristics, job and environment add layers to him and make his arc easily understood and rather significant.

The story feels disjointed to me because the action the MC will take is seemingly not dramatically connected to the events that start it off and the end goal is vague.

I know you have already written the script but just to demonstrate this is kind of what I meant with regards to dramatic connections between the actions and events:
After losing custody over his children because of his own drug addiction a prison councilor must keep his job by helping an inmate in trouble if he is to gain back visitation rights with his children.

Perhaps you could pick out similar plot points from your script to achieve the same cause and effect relationship in the logline.

Hope this helps.