Pre-order the pulse-racing new Jack Ryan thriller, TOM CLANCY DEFENSE PROTOCOL, now!

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FOR JACK RYAN, THE GREATEST THREAT LURKS BENEATH THE WAVES . . . AGAIN.

US intelligence is reporting turmoil in the Russian navy. Their deadliest submarine, the Belgorod, has unexpectedly launched. Who authorised the departure? What mission is it on? And, most disturbing of all, what weapons do the giant doors on the sub's bow hide?

It's been four decades since a similar incident with the Soviet sub, Red October, ended happily, thanks to a young CIA analyst named Jack Ryan.

Now, President Jack Ryan finds himself with fleets of ships, squadrons of jets, and teams of SEALs at his command, but what he doesn't have is insight into the plans of the Belgorod's commander. It falls to a younger generation of Ryans to do the dangerous work that will reveal that information.

But there's always a price to be paid. When the final moments tick away, will Jack Ryan have to choose between the safety of his country and the safety of his child?

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Reader reviews for ACT OF DEFIANCE

'Undoubtedly one of the best books of the series. Riveting, integrating political and military aspects, with surprising shifts and turnings'

'Netflix and prime should be fighting over the movie rights for this great read'

'The author definitely knows his subject and is well informed with the politics and command structure. The story is well constructed and leads to a good climax. Well worth the read'

'Loved the introduction of new Ryan characters. A show-stopper book and a must read. Can't wait for the next one'

Very good read; a completely absorbing plot and, as always, the final outcome fits the bill'