In this amusing sexploitation "roughie," cult director Doris Wishman prefigures her two secret agent sex-films with Chesty Morgan (Double Agent 73 and Deadly Weapons). Sandy, Nancy and Ginny are three attractive young women who discover that they are long-lost sisters when their mysterious mother is murdered. It turns out that she was a Mata Hari-like spy, Agent 73 of the A.I.C.. She leaves them a gorgeous mansion and guarantees each a million dollars if they can avenge her strangulation murder within one year. The rest of the brief running time is spent hunting for the killer, which -- in a Wishman film -- means that the heroines get to lick bananas, do naked dances, and have sex with many ugly, hirsute men. Just to keep viewers interested, a man has his throat slashed with a razor, another gets a pitchfork in the back, a cripple is shot, and a woman gets stabbed with garden-shears before being hung naked from a showerhead. Wishman includes some interesting vintage Vegas street-scenes, and porn star Levi Richards appears briefly. For a zero-budget sexploitation film, The Immoral Three is not bad, and it is certainly not Wishman's worst.