The challenge was set by England's interim defence coach Paul Gustard, who is the architect of the 'Wolf Pack' culture at Saracens and famed for his maverick coaching techniques.
Gustard, who brought live wolves and pythons into Saracens training sessions last season, is filling in as England's defence coach while Andy Farrell is on British and Irish Lions duty.
And he turned to Robert Louis Stevenson's tale of Jekyll and Hyde to emphasise his desire for England to unleash the beast within when they tackle a South American XV on Sunday and then Argentina in a two-Test series.
"What we did at Saracens was create an identity with the defence," Gustard said.
"I don't like to present mundane things. I use different stories, something I feel might have some relevance.
"If you take Jekyll and Hyde you think of a split personality.
"You have the good doctor who has good morals, he has a got a good personality, he is a family man, he is a benevolent man, he is a kind man. And when it comes to night time he turns into this villainous, mad creature.
"Defence in rugby is quite similar. During the match the players need to make calm, rational decisions, to be disciplined and composed.
"When it comes to tackling, I need them to be physical, I need the monster to come out of them. Rugby is about dominating the gainline.
"We have a pack mentality at Saracens and there are a couple of things I could do here, and that may surface next week if I feel I need to spice things up."
Gustard was the logical choice to fill in for Farrell because they worked together at Saracens and the club operate the same defensive system as the national team.
England did not concede a penalty against the Barbarians last Sunday until after the hour mark and the challenge is to build on that disciplined defensive performance against the CONSUR XV.
"This defensive system has been my job for the last five years so for me it is relatively seamless to continue the brilliant work Andy has put in place," Gustard said.
"This is a different group of players so it is about bringing new things to them and they are picking it up quickly.
"This England side will be very committed, defend with tenacity and ferocity and a desire to get the ball back."
England confirm their team for the Montevideo match on Friday and it is set to be dominated by Northampton players, who have been given a chance to "get straight back on the horse" following their Premiership final defeat.
Tom Wood will captain the team, while the likes of full-back Ben Foden, lock Courtney Lawes, scrum-half Lee Dickson and hooker David Paice will all be pushing for Test recalls.