What would you do if you could travel in time and relive – or, more to the point, change – an event from your past? Would you ace a failed interview for a job you really wanted? Buy a bunch of once-cheap stock in Apple Computer? Throw a ball again for your beloved childhood dog?

When the gangly and newly 21-year-old Tim (Domhnall Gleeson) is told by his dad (Bill Nighy) that the men in his family have always had this ability, he knows immediately that he won’t use the power for fame and fortune – for him, it’s all about love.

That’s the premise of About Time, a broadly sentimental romantic comedy from the man who wrote the book – or at least the screenplay – on that genre. Richard Curtis has been the screenwriter for Four Weddings and a Funeral (1994), Notting Hill (1999) and Bridget Jones’s Diary (2001), and he wrote and directed Love, Actually (2003), already something of a contemporary holiday classic.

Curtis’ films are not without their common traits: They usually take place in and around London, with well-educated British types living cool but not showy contemporary lives; there’s typically a sassy but funny roommate around, tossing off one-liners; and don’t be surprised if a voice-over narration tells you what the movie is already showing you. They’re also smartly written, brightly funny, and suffused with enough earnest emotion and sadness to win over the most hardened viewer.

Those cards are all dealt in About Time, which wisely decides against wasting effort on explaining its sci-fi conceit. Instead, it simply sends Tim into the timestream to make the most of an opportunity to kiss a girl on New Year’s Eve, or to plan an awkward seduction of the knockout (Margot Robbie) who’s staying with his family for the summer. It would be easy to cast Tim’s actions as those of a dark lothario, but he’s not looking to trick women – he’s just trying to improve himself.

Then he meets Mary (Rachel McAdams), an American expat, and everything clicks – for them, and the movie. Settling into a mode of domestic bliss, About Time stops being about romance and discovers a broader idea of love – as Tim uses his power to help his sister and his friends; to explore and fine-tune his life and his relationship; and to deepen his bond with his father.

Nighy, the British character actor whose career took off after a key role in Curtis’ Love, Actually, is in fine form here; as Tim’s dad, he offers the sage wisdom of a man, thanks to his temporal powers, is literally wise beyond his years. The central love story in About Time is well assayed by newcomer Gleason and seasoned pro McAdams (who ironically played a similar role in 2009’s The Time Traveler’s Wife), but Nighy’s wry warmth in the background adds a rich depth to this amiable story – reminding us that love is all around, and in a variety of forms.

(IMAGE: Rachel McAdams and Domhnall Gleason in About Time. Photo courtesy of Universal Pictures.)