Scarlett Johansson in Lucy.

What starts out as a potentially great movie winds up being merely good.

Scarlett Johansson stars as the title character in Lucy. She’s an American living in Taiwan who gets mixed up with the wrong people—and winds up not only as a drug mule, but a drug mule with a highly experimental drug placed inside her lower stomach. When the drugs start to leak, Lucy winds up using her brain to full capacity—resulting in her ability to control her body and the forces around her.

Luc Besson directs with his usual visual competence, and Johansson is great in the title role. The problem is that the film feels as if it is going to some great place—and then it suddenly ends, at 89 minutes. Granted, it’s a good 89 minutes, but I was left feeling a bit unfulfilled.

Morgan Freeman shows up as a scientist who knows a lot about brains, while Min-sik Choi (the original Oldboy) plays a true bastard of a bad guy.

Surely, the premise is total bullshit, but the resultant mayhem is fun bullshit. I just wish Besson had a more-complete story to tell.

Lucy is playing at theaters across the valley.