As 'Game of Thrones' fans will tell you, a lot of stellar work can be undone if the finale fails to live up to the hype.
t the beginning of the final chapter of the most successful period in Irish rugby history, there are fears that Joe Schmidt's Ireland have run out of steam.
When they last took the field to face England, Ireland were riding the crest of a wave. Within minutes, they were dashed on the rocks and by the end of the Six Nations they had lost ground on their rivals.
Through thick and thin, the coach has stuck with his senior players in the belief that they will deliver for him when it matters most.
As he rightly said this week, the only tournament that matters in 2019 is the one coming in less than a month's time. All of the difficult days of the spring just past will be long forgotten if Ireland get it right in Japan.
Even more than the Six Nations, these warm-up games will not linger long in the memory once the real action gets under way but right now this clash with England is very important indeed and not because a win would put Ireland on top of the world rankings.
Reaching No 1 spot for the first time in the country's history is not to be sniffed at, but Schmidt would trade that achievement for a cohesive, impressive performance and a clean bill of health on tonight's flight home.
Out-half, second-row and right wing aside, this is Schmidt's first team and his belief in the players does not appear to have been shaken by their poor performances in the first half of 2019.
The coach has rallied around a leadership group that collectively lost form in the Six Nations. The coach will live or die by his leaders.
It is time they repaid his faith with a performance that reminds everyone of why they were considered serious World Cup contenders eight months ago.
Johnny Sexton and Joey Carbery's absence will hurt the team, James Ryan will also be missed and Robbie Henshaw would certainly add to the equation, but 16 of the 23 players were involved in the Grand Slam win at this venue 17 months ago.
They won't fear England.
Eddie Jones' men are a week further down the track than Ireland and the Australian has named a team laced with power and pace.
As a first outing of the season for 12 players, it is a baptism of fire. Going from warm-weather training in Portugal to tackling the Vunipolas is quite a jump.
It is an exercise in sinking or swimming, but given Schmidt needs his main men to be fit and firing in four weeks there is no room for treading water.
Training in the high temperatures on the Algarve may pay dividends in the Japanese heat, but it could take its toll at Twickenham where forecasters are predicting temperatures will hit 30 degrees.
"It's a risk. But it's a risk that we were always prepared to take because you've got to play the long game," Schmidt said.
"There's only one tournament this year that we have to go after and as much as Saturday is a Test match, and it's a Test match against an old foe and they'll be up for it, they've had two Test matches already, a lot of our players haven't played yet, they may have a little bit of an advantage there... they freshened up this week and had a couple of days off at the start of the week because they're probably a little bit ahead of us in their preparation.
"But your timing, you want to make sure that you periodise it right so that we're on an upswing by the time we get to that September 22 game and so an August 24 game comes a distant second.
"So for a little bit, if we're carrying a little bit of fatigue in the legs, I'll accept that and I don't think that we'll accept it easily because we want to be a little bit competitive on Saturday, but if this last eight days is good preparation for September 22, then that's what counts most."
When he looks around the dressing-room this afternoon, Schmidt will see players who have delivered for him.
He puts huge stock in players having been there and done that, but as Rory Best alluded to in these pages, they cannot rely on past performances as a guarantee of future displays.
The captain is one of those who must repay the faith the coach has placed in him.
He'll be acutely aware that Gordon D'Arcy this week named him as one of a number of Ireland front-liners who are past their best and, at 37, it is hard to argue the case.
At most, the Ulster man has 10 more games left before he retires and he looks in good nick as he approaches his final push. His lineout and scrum work must be on point and, while there is no need for him to get overly concerned about getting his hands on the ball, he must bring huge industry to the ruck and maul.
Beside him, Cian Healy and Tadhg Furlong will be tasked with setting the physical tone.
Along with James Ryan, Healy was Ireland's best player last season but Furlong dipped below his Lions standard. The summer off should result in a return to form.
Behind them, Iain Henderson has another chance to put his hand up to become Ireland's lineout leader along with Peter O'Mahony. Devin Toner may be an increasingly concerned figure as he watches Jean Kleyn become more and more central to Ireland's plans.
In the back-row, Ireland can't afford O'Mahony to have one of his quieter days. CJ Stander knows Jack Conan is breathing down his neck, while Josh van der Flier is tasked with slowing England's ball so the big men don't get a steady, undisrupted supply.
Conor Murray endured a difficult 2018/'19, but indications are he's primed for a big World Cup. He will be tasked with helping Ross Byrne adapt to his surroundings.
Bundee Aki will help ease the physical load, while Garry Ringrose has a clean slate to put a forgettable campaign behind him. Out the back, Rob Kearney will be better able to cope with England's kicking game, while Jordan Larmour has a real opportunity to put pressure on for a starting spot.
They will be tested. England haven't gotten any smaller since the sides met in Dublin and the decision to select two opensides means they'll go after Ireland on the ground, but it should mean the visiting team can cause huge disruption to the lineout.
Ireland have been working on their attacking phase play, but much will depend on their work in the collision. They can't allow themselves to be bullied.
If they end the day as the world's No 1 team, they'll be in bonus territory and much of the negativity around the squad will dissipate.
But even a good performance and an avoidance of injury could change the downbeat narrative around this team and put them back on track for a grand finale.