Yet another Nazi/British spy tangle--with the usual elements (a plot to assassinate Hitler, secret cooperation between Canaris and London, famous cameos, triple-agents) given a straightforward but uncommonly slow-moving treatment. Abwehr agent Otto von Bredow makes 1942-43 contact with grand old UK spy-veteran Jackie Bellingham in Portugal. The message to SIS chief Sir Stewart Menzies in London? That Canaris' Abwehr group will give the British info about a rival German SD agent within the SIS (they don't know his name)--if the SIS will, with secret Abwehr support, kill Hitler during his upcoming conference with Mussolini on the isle of Rhodes. (And all of this would lead to a UK/Germany peace.) Sir Stewart gives his okay; Britain receives the German data, which should enable them to finger the traitor; Bellingham goes to Cairo to put together a special commando team for the Rhodes attack on Hitler. But, meanwhile, the SD has gotten a warning about the assassination scheme from their agent/traitor, code-named ""Turquoise."" Furthermore, it seems as if Sir Stewart isn't telling his old pal Bellingham everything he secretly knows (along with PM Churchill) about double-agent ""Turquoise"": yes, as most veteran WW II-espionage readers will guess early on, ""Turquoise"" is really a crucial triple-agent (exactly like the one in Hans Herlin's The Last Spring in Paris, p. 1013)--so Sir Stewart is determined to keep him ""firmly and unquestionably operational, whatever the cost."" Thus, the assassination mission--now in full progress, involving Greek partisans--is doomed from the start. And there'll be lives coldly sacrificed on Rhodes, with both German agent Bredow and UK agent Bellingham suffering pangs of disillusionment and guilt. Taylor does have one extra twist up his sleeve: ""Turquoise"" is really a quadruple-agent (with a famous name). But, despite some worthy attempts at downbeat ironies and textured characterization, this is an overlong, just-serviceable variation on a familiar formula--less involving than, among others, the above-mentioned Herlin version.