This is the fourth in the 1960 west German Dr Mabuse series.While it is above average for the series it does mean that it is a cut above most other thrillers of the time.
A young actress (Karin Dor as Liane)in a Grand Guigonol/circus troupe seems to be haunted by a ghost.A government operative is investigating the troupe and meets his end via a killer clown.The FBI sends in Joe Como(Lex Barker from the 2nd in the series,The Return of Dr Mabuse).Joe and Liane cross paths.
Liane's former boyfriend had created an invisibilty gadget.But he presumably was killed in a car accident.Dr Mabuse and his gang think that Liane knows the whereabouts of the invisibilty device.The boyfriend is in fact not dead but horribly mangled due to the crash.He is using the gadget to stay near his love.
Mabuse & Joe Como both attempt to wrest the gadget from the boyfriend.But it looks like Mabuse may have the upper hand and chaos will reign supreme.An invisible gang of super criminals would be hard to beat.
In the series of Mabuse thrillers this one grades out at #5 of the 6 but way above the stinker Death Ray Of Dr Mabuse.It would be nice to see this film get the dvd treatment.