Unwin seems to have had quite a lot of fun engineering the plot’s Mobius strip twists and turns .... [The hero’s] refreshing attitude helps wind the mainspring of an SF subgenre that’s grown a bit lax from overuse.... If Michael Crichton’s 1999 novel Timeline had starred as astringent a lead character as Joad, maybe its 2003 movie adaptation would have been better.... Original touches and a misanthropic protagonist keep this clever time-travel tale ticking along nicely.