When a plague of friendly London ghosts turns violent, a disillusioned exorcist must learn to put aside his differences with the people in this world and find the source of the evil.

It sounds like this could be a very original, entertaining movie. I like it. It is an original premisse.

'Learn to put aside'... sounds like an inner journey. It is hard to sell a movie concept on this. Loglines should first and foremost focus on the visual aspects of the story concept.

"Find the source" may be more visual in the movie but from this description we cannot imagine what it would look like.

Perhaps 'his differences with the people in this world' is also somewhat too generic. Can you be more specific? Who is the antagonist?

And surely, once he's found the source of evil, he must eradicate it, right?