Original touches and time-travel intrigue keep Murphey’s clever fourth installment in the Physics, Lust and Greed series ticking along nicely. 

Marshall Grissom and Marta Hamilton are two semi-retired time travelers trying to start a new life together under the warm Caribbean sun. After proving too risky and raising too many ethical dilemmas, their time-travel program was unofficially shut down. But even with time travel on ice, suspicious Marta refuses to let her guard down. Marshall is never really relaxed about anything, so his quirky nature likewise keeps him alert to danger. It’s a good thing too, because someone is after Marta and Marshall and it’s impossible to know who it might be or from when their adversaries come.