Rose (Brooke Adams) was discovered in a small dinghy drifting in the Atlantic by a fisherman and his son; she was suffering from shock and it is only now that the memories of what happened to her are beginning to return. She had been a member of a tourist party on a small boat in the Caribbean, and the craft was not in great shape, as they found out when the irascible Captain (John Carradine) began making excuses for the breakdowns they suffered. But then something strange happened: the daylight turned a sickly yellow and then winked out altogether. It was as if night had fallen...
As Nazi zombie movies go, Shock Waves has to be considered one of the best and even started a shortlived trend for such villains in horror movies of the late seventies and early eighties. The writers, consisting of director Ken Wiederhorn, John Kent Harrison and Ken Pare, managed the tricky feat of not making their film too distasteful by not emphasising the ghastly past of the S.S., which their zombies belonged to: here the baddies were more indebted to George A. Romero's Night of the Living Dead than anything based in truth and the work was all the better for it.
Funnily enough, with the opportunities for gory death that the premise threw up, this independent shocker - made in Florida - opted to go for creepy atmosphere instead, so when the zombies do bump off the cast, they drown their victims rather than, I dunno, tear their heads off or something. It's a pity that the filmmakers decided to put the flashback structure on their efforts because with that opening that has Rose being found alone, we are all too aware of who the survivor will be and it means for the rest of the film we're waiting for the other characters to die.
Thanks to some excellent makeup by Alan Ormsby, a writer and occasional director himself on other projects, the undead Nazis look undeniably impressive and Wiederhorn includes a wealth of shots of his menaces emerging from the water around the island the tourists are eventually grounded on. It's an effective series of scenes, and although essentially repeated over and over throughout the film, you never get tired of seeing those goggled, uniformed, jackbooted bad guys impassively making their way around the landscape - and occasionally walking around underwater, too. They knew they were on to something potent with these figures.
As for the living cast, Brooke Adams was on the brink of minor stardom and is plainly on her way to bigger things here. The tourists may be drawn from stock, with the overbearing know-all or the hunky hero or the coward who jeopardises them all well to the fore, but each actor does something to make them distinctive. The always welcome guest stars are Carradine, having fun with his short-tempered role, and Peter Cushing, the sole occupant of the island, an ex-S.S. officer meant to keep the forces in check, but noticeably failing to do so. He fills in the backstory about the Nazis wanting to create a race of supersoldiers by supernatural methods, and ending up with these killers, a clever premise that is neatly capitalised on by Wiederhorn and company. Shock Waves does suffer from a rather too-basic plot, but those images are strong, with the power of a really good nightmare. Spooky electro-music by Richard Einhorn.