In the tunnel Henry asked: “If it’s the same Tripod, the one that’s been following us, why hasn’t it taken us before now?” In screen-writing as in courtroom lawyering, never ask a question to which you do not know the answer. Henry is right to be baffled, and Beanpole’s reply, “Maybe it wants to know where we will go, and what we will do,” is not entirely satisfactory.

This all comes about because of the first really significant change from the plot of the book. In the book, it is Beanpole deactivating the button which leads the Tripod to stop just following and attack, which makes perfect sense. On television, cause and effect are the wrong way round: it is the Tripod’s attack which leads Beanpole to deactivate the button. In that switched version, then, the Tripod must have attacked simply because it was bored of passively following, and wanted to provoke the boys.

The show has followed the book in every important way up to now, but sooner or later it was going to have to diverge. If anything, the show has waited until the last possible moment, because there is now very little source material left in The White Mountains. We’re halfway through chapter nine, of only ten. What “should” happen next is a final battle with the Tripod, and then some cursory closing pages barely describing the Alps at all. Despite the title of the book, and what many of its painted book covers imply, barely any of the action happens anywhere near the Alps: they are only a symbolic goal, a metaphor.

On television it’s far too soon for any final battle — we have five episodes yet to fill — and not to show the Alps would be a let-down. So our show needs an off-ramp from the plot of the book in order to reach narrative space to tell further stories. That’s why this plot transposition was made, with the Tripod attacking first, whatever the small cost in logic.

And so the remainder of series 1 interleaves about four episodes of new, non-book material into what little remains of the original. The balance of power between our two authors shifts as a result: these final five episodes are “by” the 1980s screen-writer much more than they are “by” the 1960s novelist. Though the new events are tenuously still connected to brief moments in the book, they can now be told with more freedom, not being tied down to a first-person narration any more. This means the action can be shared a little more equally between the trio, giving Henry and Beanpole more to do. And a new director and production unit take over, so it’s a fresh start all round. (That said, the exact handover point between production teams is unclear to me: which director handled the railway tunnel sequence?) Previously unheard musical themes accompany a change of both landscape and season. Whereas the book ends in late summer, television runs right on into winter.

For a fan, of course, it would be sad to think of cutting these roughly four extra episodes, which expand our show’s fictional world and give us some very affecting character moments. But it could easily have been otherwise, with the book given a 9-part rather than 13-part adaptation. The trouble is that the book has a strong and continuous plot, and because these bonus incidents aren’t part of that structure, all they can ever be is incidental. There’s little sense of peril, and the next three episode endings will be notably lower in jeopardy than those for episodes 4 to 8. And nothing will ever be so visceral or desperate again as what we are about to see with the knife and the button.

Next: Episode 9 ● Prev: Episode 8 (second half)