Much more than a trace

“Without a Trace” wraps up its first season tonight without a flaw.

The conclusion of a two-part episode called “Fallout” (10 p.m., CBS) offers plenty of the usual suspense, but the biggest surprise is how it explores love and loss with such devastating urgency.

The episode, written by Hank Steinberg and directed by Kevin Hooks, shows how one heartbreaking crime spawns another when the husband of a 9/11 victim from the World Trade Center takes several hostages. It also conveys, in the growing weariness of FBI search team leader Jack Malone (Anthony LaPaglia), how we can die a little with every passing day.

Last week, Barry Mashburn (Tom Irwin) kidnapped Sydney Harrison, his wife’s former boss, and when the ransom exchange at a New York City bookstore went wrong, he took the undercover Samantha Spade (Poppy Montgomery) and a handful of bystanders hostage.

Tonight, the hostage crisis becomes increasingly volatile as the distraught Mashburn ends up with little to lose and his revenge motive becomes clear.

After Spade gets shot during a struggle, Malone tries to negotiate her release by offering himself as a hostage. Meanwhile, the rest of the FBI team searches desperately for the original kidnapping victim.

As we get to know his complicated character, Mashburn becomes increasingly sympathetic, and Irwin’s portrayal ever more fascinating. As we also learn more about Malone’s lonely life, LaPaglia delivers another outstanding performance as well.

In the hands of these actors, the juxtaposition of these two men illustrates the fragility of life, and the importance of every instant, with rare power.