It's probable you've seen them, likely you've even been approached by them, and certain you've at least heard of the Jehovah's Witnesses.

Joel P. Engardio and Tom Shepard explore the intricacies of the religious group in their documentary "Knocking."

The documentary follows two separate families, both including members who are Jehovah's Witnesses and who are not. Audiences get to hear both sides of the story, and that allows viewers to really get a feel for the ups and downs of the religion.

"Knocking" examines every angle of the issue imaginable. The documentary manages to progress with almost no narration by the directors. It relies on interviews with people affected in various ways by the Jehovah's Witnesses' beliefs.

The documentary is informative but also engaging. The stories are told in an interesting, sometimes even suspenseful, manner.

Viewers learn, among many other things, that a major belief of Jehovah's Witnesses is that blood is holy. As a result, members of the faith cannot receive blood transfusions. Witnesses carry a card in their wallet that says "no blood" in case they are in an accident and unable to tell doctors of their policy.

Throughout the course of the documentary, viewers get to know a young member of the faith who needs a liver transplant — without using blood. The documentary teaches audiences about more than just a religion.

Viewers learn about history, legal precedent and groundbreaking scientific discovery.

The film touches on values that rest in the heart of all people — freedom of religion and freedom of expression.

Check out "Knocking" at the East Lansing Film Festival on March 24. For more information on the documentary, visit www.knocking.org. For information on the film festival, visit www.elff.com.