“Suicide bombers are easy to spot,” ex-military cop Jack Reacher reflects at the outset of Lee Child’s superb new thriller, Gone Tomorrow (Delacorte, 427 pages, $27). “They give out all kinds of telltale signs. Mostly because they’re nervous. By definition they’re all first-timers.”

The irrepressible, nomadic Reacher, today’s quintessential series hero, believes he’s facing just that on board a late night subway train as it jets through New York City’s endless cavern of tunnels. But even that speed is nothing compared to the high-velocity, violence-riddled path Reacher carves through all in his way to find the truth after the suspected suicide bomber commits suicide instead.

That path leads him to Sen. John Sansom, a war hero whose Special Forces past is shrouded in a darkness that especially nasty Afghani terrorists want to bring into the light. Their leader, Lila Hoth, makes for one of Reacher’s best adversaries and Child’s most villainous creations, rivaling Ian Fleming’s Rosa Klebb (From Russia, With Love) as the greatest female villain of all time. She’s in command of a small army while Reacher, of course, is on his own. As he says, “Just do it was our motto, well before Nike started making shoes.”

And, boy, does he ever, taking it to the bad guys with an aplomb that has become the signature of the greatest action hero since James Bond. Child is always good but his lucky 13th entry takes this series to new heights. A magnificent achievement in every respect. Flat-out great.

With that in mind, it seems patently unfair to compare any fledgling thriller writer to Lee Child. But in Andrew Grant’s case, comparison is virtually inescapable, since he is Child’s younger brother. And his first effort, Even (Minotaur, 340 pages, $24.95) makes a pretty good case for his forging his own footsteps instead of following those of his practically legendary sibling.

“When I saw the body,” Even opens, “my first thought was to just keep on walking.”

Sound familiar? It should. Grant’s effortlessly staccato style resembles his brother’s just enough. The difference is that his hero, David Trevellyan, is still in the employ of a secret offshoot of the British government, doing many of the same things as Jack Reacher, only with official sanction. And if he had just kept on walking, he’d have been on to his next assignment instead of embroiled in a complex conspiracy involving the FBI, private government contractors and various bad guys of ever-shifting loyalties — all somehow connected to the serial murder of freight-train-hopping tramps.

Given that the lone hero is so much a part of American folklore and mythology, it seems strange that two of the writers following that tradition best are both British. Once Grant’s writing finds the kind of economy Trevellyan displays in his fighting skills, he could draw even (no pun intended) with his fabled brother. For now his debut effort stands on its own as a well-oiled machine of a thriller that satisfies at every turn.