Plunkett replaces Finn for ODI, T20 leg
The news is a considerable setback for Finn, although England expect him to be available for the World T20 in March. Having originally been left out of the Test tour of South Africa due to a foot injury, he recovered quicker than anticipated and, after his late call-up, bowled beautifully - though without much reward - in the first three Tests. He will remain in South Africa to begin his rehab before returning to England after the final Test.
Plunkett, currently with the England Lions in the UAE, was unfortunate to miss out on selection originally. He bowled with impressive pace and hostility in the two T20s he appeared in against Pakistan in the UAE - claiming three wickets in each of the games - at the end of November but missed out to the likes of Chris Jordan and Chris Woakes, who it appears are being groomed as England's death bowlers.
There was also a suggestion that Plunkett, for all his hostility when it most counted, had not always impressed as much as his team-mates in training sessions. Having spent a fair portion of 2015 on tour with England but rarely made in into the side, some frustration, even disillusionment, was probably inevitable.
"I was disappointed not to be in the squad in the first place," Plunkett said. "But I came back here with the Lions determined to play to my best and show I'm still ready if they need me. Then obviously I saw Finny was injured, so I did wonder, and I got the call from James Whitaker.
"We've only played a warm-up game out here so far against the UAE but I felt in pretty good rhythm straight away and clicked it up to a decent pace. From the end of last season I've pretty much been bowling all the time, and I just had a few weeks off in December."
George Dobell is a senior correspondent at ESPNcricinfo