Great Northern? - Arthur Ransome

'I was wrong,' said Captain Flint. 'He's not mad but bad. It isn't only eggs he wants. He wants to take the credit for it. You're quite right. It's up to us, it's up to the ship, to see he doesn't.'Dick's birdwatching discovery turns the cruise of the Sea Bear into a desperate chase. Not only do the Swallows and Amazons have to prove the facts of the case but they also have to dodge the savage natives and evade the ruthless pursuit of a fanatic egg-collector, determined to kill a pair of rare birds and steal the credit. Fortunately, Nancy has a few plans.