Bad Luck and Trouble (Jack Reacher) / Lee Child,

From a helicopter high above the California desert, a man is sent free-falling into the night . . . and Jack Reacher is plunged into the heart of a conspiracy that is killing old friends.
 
Reacher has no phone, no address, no ties. But a woman from his former military unit has found him using a signal only the eight members of their elite team would know. Then she tells him about the brutal death of one of their own. Soon they learn of the sudden disappearance of two other comrades. But Reacher won’t give up—because in a world of bad luck and trouble, when someone targets Jack Reacher and his team, they’d better be ready for what comes right back at them.