Stormchild by Bernard Cornwell
Tim Blackburn's wife died in a ball of flame in the Channel, victim of a mystery bomber. His son had died years earlier in Northern Ireland, killed in a terrorist attack. And his daughter Nicole had vanished in the North Pacific after joing an outlawed organisation called Genesis dedicated to saving the planet, by violence if necessary.
The police think Nicole might have been involved in the death of her mother, but Tim won't believe it. And he means to prove it.
With nothing else to live for, Tim goes in search of Nicole in his yacht Stormchild. He hopes to rescue her from the clutches of Genesis. But where would a secretive organization of ruthless environmentalists hide? And even if he does find Nicole, will he be a welcome visitor?