When an unusual classified ad inspires three cynical Seattle magazine employees (Aubrey Plaza, Karan Soni and Jake Johnson) to look for the story behind it, they discover a mysterious eccentric named Kenneth (Mark Duplass), a likable but paranoid supermarket clerk, who believes he’s solved the riddle of time travel and intends to depart again soon. Together, they embark on a hilarious, smart, and unexpectedly heartfelt journey that reveals how far believing can take you.

Quirky sci-fi comedy wears its heart on its sleeve as it plays tricks with time.

SYDNEY FILM FESTIVAL: 'Wanted: Someone to go back in time with me. This is not a joke. Must bring your own weapons. Safety not guaranteed. I have only done this once before."

So runs a classified ad in a Seattle newspaper, the catalyst for a series of wacky, amusing and touching events in this highly original film which was a hit at the Sundance Film Festival, marking an impressive debut from director Colin Trevorrow, a graduate of New York University’s Tisch School of the Arts.

Inspired by an ad in a survivalist magazine in the mid-1990s, Safety Not Guaranteed is an appealing blend of sci-fi fantasy, romance and comedy written by Derek Connolly, who met the director when they were interns on Saturday Night Live.

Central to the film’s charm is that the question lingers of whether the putative time traveller is a nutcase or actually sincere. Mark Duplass (better known as the co-director with his brother Jay of the indie films Jeff, Who Lives at Home and Cyrus) is terrific as Kenneth Calloway, the enigmatic, lonely guy who places the ad.

Aubrey Plaza (of TV’s Parks and Recreation) is Darius, a gloomy young woman who works as an intern at a Seattle magazine. She gets the chance for a field trip when jaded staff writer Jeff (Jake Johnson) takes her and a fellow intern, nerdy college student Arnau (Karan Soni), to the coastal town of Ocean View to track down the mysterious Kenneth for a magazine profile.

Jeff is quickly distracted as he seeks out an old high school sweetheart (Jenica Bergere) with unpredictable results, entrusting Darius to find Kenneth at the grocery store where he works and to gain his trust. Darius claims she wants to join his mission while she figures out if he’s bonkers, playing an elaborate joke or is actually determined to wind back the clock.

Kenneth takes her for target practice and leads her through various physical exertions in a hilarious sequence, confides that his plan is to go back to 2001 and reveals his reason.

She too has a motive to revisit the past. He seems paranoid and tells her he’s being followed by government agents, which turns out to be true.

The chemistry between Plaza and Duplass imbues the film with a surprising emotional depth

In this instance time travel could be a metaphor for a desire to return to an earlier time when life was more enjoyable and a bright future beckoned, a concept most of us can all relate to.

Duplass is convincing as a vulnerable oddball who very nearly manages to make his far-fetched idea seem plausible as Kenneth lowers his guard to Darius and she develops feelings for him.

Plaza deftly handles the transformation from a cynical, prickly misfit who confesses 'I expect the worst and try not to get my hopes up," into a sweet, caring person. Soni adds to the fun as the butt of Jeff’s sometimes cruel jokes and jibes.

Despite the age difference in their characters, the chemistry between Plaza and Duplass imbues the film with a surprising emotional depth and a believable romance while the sub-plot involving the immature Jeff and his lost love is a fascinating counterpoint.

Trevorrow adroitly manipulates the shifts in tone, concocting a very likable and engaging movie: he’s a real talent to watch.