As in 2004’s “Birth,” the idea of reincarnation is handled in a mystical rather than mysterious way. “P.S.” is not a ghost story but a love story. Lives are interrupted by a cataclysmic coincidence, yet there is also an audacious amount of subtle and wry humor in the margins. “P.S.” is a weird movie, with laughter arriving uninvited to the most solemn occasions.

Director Dylan Kidd burst on the scene in 2002 with the critically acclaimed “Roger Dodger,” which came with a particularly strong recommendation from The New Yorker. “P.S.” finds him with an even firmer grasp of character and scene. Linney, the Nicole Kidman of the indie world, is as marvelous as always and is well-supported by veterans Gabriel Byrne as her ex-husband and Marcia Gay Harden as her harpylike sister.

But pay most attention to Grace, endlessly watchable during this stupendous rendition of a college kid, a half-formed adult reaching for the gravity of the world with the remnants of innocence still clinging to him. This sizzling story is best attended with the same sanguine insouciance F. Scott appends to an afternoon romp: “Awesome!” — Wayne Melton