A medical student develops a serum to resurrect his dead fiancee only to fight for his life because she was resurrected from hell after being transformed into a demon. (29 words; THE LAZARUS EFFECT)

Hello, 30 word is not bad but there is?some redundancy (resurrect/resurrected). Then I think that the details about the technique for resurrecting her are not very interesting in the economy of the logline. Maybe it would be better to include some more details about the actual plot (a boy fighting a demon for at least one hour is all that we know). Maybe you can explain what kind of plan he has to kill the demon? Or you can tell where the fight take place (in a medicine school? At a big medicine students party- I like this one as there are usually some macabre jokes to play with!). ?Or you can explain what kind of demon she is (what does she wants? revenge? kill everyone?).

This is still too elusive about the plot but what about:
“When a?medical student resurrects his bitchy dead fiancee, he must fight for his life as she’s really form hell.”