A mad doctor named Zanoff uses a drug to bring himself back from the dead after his execution in prison. Dick Tracy sets out to capture Zanoff before he can put his criminal gang back together again.

International spy Zarnoff's attempt to destroy an industrial canal with a remotely piloted boat is foiled by Tracy, who is saved by Steve Lockwood's plane just in time to survive the blast.

Tracy escapes accidental execution by his own men just in time; he finds a lighthouse man named Cappy locked away; Zarnoff's men disable a lighthouse that's keeping ships safe from the suicide reef.

Tracy saves Latin American President Mendoza by using a spotlight on a barge to warn the President's yacht of dangerous rocks; the barge catches fire while Tracy is engaged in a fight, and Zarnoff's men, led by Robal, escape.

The G-Men raid on the harbor, where Zarnoff's men are fighting Tracy, ends; Tracy survives but Zarnoff's lieutenant, Robal, escapes.

After preventing Zarnoff from derailing a train loaded with $2.5 million dollars worth of gold, Tracy follows his only lead to Norton Dam; he and Steve search for Zarnoffs men at the dam.