Greetings again from the darkness. These days most tend to define anti-aging as the desire to look younger … vitamins, lotions, botox, and plastic surgery all thrive in a society obsessed with never looking old. Co-directors David Alvarado and Jason Sussberg introduce us to two of the world's leading anti-aging scientists, and neither of them specializes in facelifts.

Bill Andrews is 61 years old, runs ultra-marathons, and his catchphrase is "cure aging, or die trying". Dr. Andrews is convinced human beings can live forever. Fifty year old Aubrey de Gray is the heavily bearded (think "Duck Dynasty") founder of the SENS Foundation, which is dedicated to stopping/correcting the aging process. While some, especially the old guard of biologists, label their missions as pseudo-science, a 2011 Harvard project actually reversed aging in mice – lending credence to the work of these two (and others).

As with many frontiers in science, this subject begs two questions: Can we? Should we? One additional question fits snugly here as well: What happens if we do? Each of our scientists gets his shot at explaining his theory. The two theories actually contradict each other, leading to a somewhat friendly rivalry.

Rather than remaining focused on the science and the works of many other doctors dedicated to anti-aging, the film evolves into a character study of two distinct personalities. Bill's mission is personal as he confesses his desire to live forever, to save his dad who suffers from Alzheimer's, and to cure his best friend who has cancer. Aubrey, on the other hand, states his work is not personal in the least. His sights are set on saving humanity.

The personal side of these two dominates the film. We see a great deal of Bill running – sometimes while giving interviews, and sometimes struggling to breath while (twice) attempting a 138 mile marathon through the Himalayas. We see even more (so to speak) of Aubrey as he enjoys a nude picnic with his biologist wife, and later a glass of champagne with one of his two younger girlfriends in the woods near his California commune. These are two eccentric, but very different gentlemen who are attractive subjects for a documentary. Unfortunately the blistered feet and shaggy beard take away from the more interesting topic of curing aging.

The accusations of quackery are met with the obvious comparisons to early flight technology. We couldn't fly until we could. Will humans someday live forever? Can the aging process be reversed? It appears more likely that de Gray's SENS Foundation has a better chance of success since it has received funding, while Andrews' research company is nearly bankrupt. Very little time is given to the "What happens if we do?" question. The filmmakers assumed we would find the two gentlemen as fascinating as they do. Instead, the film left me wishing for more insight on the science, and less spotlight on the scientists.