It's every parent's worst nightmare: your kid disappears, snatched from a crowded city park without a soul taking notice. Is the situation better or worse for Tom Mullen (Mel Gibson: The Patriot, Chicken Run) and his wife, Kate (Rene Russo: The Adventures of Rocky and Bullwinkle, Lethal Weapon 4), than it would be for other families? Tom owns a global airline and is worth billions. Was their son, Sean (Brawley Nolte: Affliction), kidnapped for a hefty ransom, and hence his safety is relatively assured, or is the abduction some kind of horrible payback for the airline's union troubles, which have landed union leader Jackie Brown (Dan Hedaya: The Crew, Shaft) in prison, thanks to Tom's corporate maneuvering? Will Tom and Kate ever see their child alive again?

An FBI team, lead by Agent Lonnie Hawkins (Delroy Lindo: Gone in 60 Seconds, The Cider House Rules), sets up shop in the Mullens' Fifth Avenue penthouse, though the kidnappers have insisted that no cops and no media become involved. Plotwise, the first half of Ransom never really rises above the standard cat-and-mouse game cops and villains play in rote thrillers -- it could be anyone carrying out the kidnappers' convoluted instructions for ransom drops. And the plot twists that occur when things go bad and Mel gets mad aren't as surprising as they should be just by sheer dint of the fact that it's a Gibson character forcing the twists -- insanity is precisely what we do expect from Tom, just because of who is playing him.

Yet Ransom remains involving and tense because its cast is left free to breathe genuine life into their characters and make them real, sympathetic people, even the bad guys, who'd have been ludicrous played by lesser actors. The psychology of the mind games the kidnappers play with their own sense of human decency in the midst of their horrible crime works because it's Lili Taylor (The Haunting, The Imposters), Liev Schreiber (Scream 3, The Hurricane), and Donnie Wahlberg (The Sixth Sense) trying to find their way through this mess -- all are actors who can do a lot with little to go on, and though the script doesn't much flesh out their characters, they do. Gary Sinise (Mission to Mars, Reindeer Games), as the working-class city cop who's on the case right from the very beginning, seethes with the kind of class resentment that only a city like New York, with its huge gulf between the very richest and the very poorest, can engender, and he makes it easy to accept the rancor the Mullens raise in him. And Gibson and Russo have some of the best chemistry of any couple on film today, engaging in a comfortable tug-of-war of love, recriminations, attraction, and anger. It's almost hard to believe they aren't actually married to each other offscreen.

Directed by Ron Howard (The Grinch, Apollo 13), at best a mechanical filmmaker, Ransom is still good, diverting fun on subsequent viewings, when the surprises are spoiled and you know how it ends. But probably only if, like me, you haven't had enough yet of Mel Gibson flying off the mental handle.