Anna Kendrick, Sam Rockwell and Tim Roth are, unsurprisingly, the best things going when it comes to “Mr. Right,” a hybrid of action, comedy and romance that otherwise plays like the world’s thousandth third-rate “Pulp Fiction” knockoff.

These actors are far better than material like this deserves, and it’s impossible to be fully down on any movie that brings them together in this sort of heightened genre-bender. The script, by Max Landis (“American Ultra”), simply has a tough time generating much beyond the high-concept pitch of a young woman (Kendrick) on the rebound and falling for a nice-guy hitman with an affinity for flashy clothes (Rockwell), who is being pursued by his nemesis (Roth).

The picture works best when director Paco Cabezas lets his stars play off each other. The romantic scenes, often interrupted by stealth comic violence, have the sort of old-fashioned screwball quality that befit actors who are both talented performers and gifted showpeople.

Eventually, the charm wears off and the movie devolves into halfhearted action set pieces, playing out the string in a plot that’s utterly immaterial to the picture’s best qualities.