[2] The film documents the life of former magician, escape artist, and skeptical educator James Randi, in particular the investigations through which he publicly exposed psychics, faith healers, and con-artists.

Age and concerns over the danger of his profession and his health leads him to retire from that occupation and seek out not only a new career, but a crusading obsession that makes him a pop cultural fixture by the 1970s: As a scientific skeptic investigator and challenger to pseudoscientific and paranormal claims, which leads him to expose the deceit behind religious faith healers, psychics, and other con artists who exploit the public.

One is mentalist Uri Geller, who performed psychic feats on the talk show circuit, such as bending a spoon with minimal contact, and guessing the contents of sealed envelopes and other objects.

Randi worked closely with the staff of The Tonight Show with Johnny Carson prior to a 1973 appearance on that program by Geller, who publicly claimed at the time that his acts were performed with genuine psychic ability, and not magic tricks.

Randi had The Tonight Show staff observe strict controls over the materials that Geller would work with during his appearance to prevent any trickery or cheating.

Another target is faith healer Peter Popoff, who during his church revival meetings, demonstrated personal knowledge of people in the audience, such as their names, addresses and illnesses, which he stated was due to the work of God.

In 2012 producers Tyler Measom and Justin Weinstein visited James Randi at his home in Plantation, Florida to express interest in filming a documentary about his life.

"[4] Geoff Pevere, reviewing the film for The Globe and Mail, gave the film three out of four stars, calling it "aptly seductive", though he called into question whether the methods Randi used in the case of the Australian hoax were a form of dubious deceit themselves, stating, "The ultimate question in An Honest Liar is whether it’s possible to know so much about the method behind the magic without being fooled into believing your own act.