Professor Elwood Henderson (Byron Foulger) has invented a device, called an Orotron, which can extract minerals out of sea water. One of the minerals is gold. An organization of Nazi’s have infiltrated Henderson’s laboratory. They want the device so they can have unlimited amounts of gold.

Henderson's assistant, Arnold Hoffman (Roland Varno), is really Arnold Hoff. His secret code number is M-3. Each member of the organization is assigned a code number and a key. Each agent’s number is etched into their key. The head of the organization is called The Master Key. His identity is a secret, even from the other members of the organization. Only M-2, Gerhard Doenitz AKA Donahue (Addison Richards) knows who The Master Key is. Seven of the key holders are the head Nazis that report to M-1, The Master Key. Below them are various henchmen that do most of the dirty work.

The Nazi’s have kidnapped Henderson. Only he can make the electronic tubes needed to keep the Orotron producing gold. Gold that they smuggle to Germany to allow the Nazis to keep funding their cause. The Professor’s assistant Hoff can work the machine, but he doesn’t know how to make the replacement tubes needed when they wear out. For the time being Henderson is safe, but when the tubes no longer function and the machine stops, if Henderson doesn’t cooperate, he will be tortured.

Agent Tom Brant (Milburn Stone) is sent to find Henderson and break up the Nazi spy ring. He is working with Detective Jack Ryan (Dennis Moore) and Police Chief Michael J. O’Brien (Russell Hicks). Investigative Reporter Janet Lowe (Jan Wiley) tags along looking for the latest story. Brant has some concerns as to which side she is really on. She seems to have some tie with one of the spies, Walter Stark (John Eldredge). Unbeknownst to everyone Stark is Janet’s half brother. Using a street gang led by Migsy (Alfred ‘Lash’ La Rue) and a candy store owner named Aggie (Sarah Padden) Brant, Ryan and Janet continue to harass The Master Key and his minions. But someone close to the action is a traitor and is feeding information to The Master Key every step of the way.

“The Master Key” was released in 1945 and was directed by Lewis D. Collins and Ray Taylor. It is a thirteen chapter serial and is the 132nd serial done by Universal and its 64th sound-era serial.

There are a few things that make this serial a little different. The title of the serial is based on the name of the villain and not the hero. There are actually two heroes, Agent Tom Brant and Detective Lt. Jack Ryan. Also the cliffhangers don’t revolve around one person. Usually the victim of the cliffhanger is Agent Brant but a couple times the person in imminent danger is Janet Lowe and at least once it was Jack Ryan. The beginning chapter summarizations are done by The Master Key.

There is a lot of repetitive narration rehashing what the Nazi’s are doing. It can be a little annoying but I fully understand why they did that. There is no recap episode reminding everyone of what had happened in the last ten or twelve episodes. Also the serial itself was shown one episode at a time. Movie goers had to wait a week to see what happened next so a reminder of what has happened in previous chapters is sometimes necessary to keep the narrative cohesive.

The story is good and the acting is as well. Byron Foulger is especially good as Professor Henderson. This is one occasion were he has more than just a quick supporting role. There aren’t as many fist fights as usual or as many wild cliffhangers. What they lack in wild antics they make up for in a good story line. Not to mention that it’s fun to watch.

Alfred "Lash" LaRue was a popular western motion picture star of the 1940s and 1950s. He had exceptional skill with the bullwhip and was one of the main inspirations for the character of Indiana Jones. LaRue was one of the first recipients of the Golden Boot Awards in 1983.

CHAPTER TITLES: 1) Trapped by Flames, 2) Death Turns the Wheel, 3) Ticket to Disaster, 4) Drawbridge Danger, 5) Runaway Car, 6) Shot Down, 7) Death on the Dial, 8) Bullet Serenade, 9) On Stage for Murder, 10) Fatal Masquerade, 11) Crash Curve, 12) Lightning Underground, 13) The Last Key.