Samantha Murray won a brilliant silver medal to maintain Great Britain's record of having picked up a modern pentathlon medal at every Olympics since the women's event was introduced to the programme in Sydney in 2000.
The 22-year-old from Clitheroe in Lancashire was ranked 78th in the world in February but has had a stunning season, capped off by a superb performance in Greenwich Parky.
Murray went into the final event, the combined run and shoot, in fourth place but overhauled Brazil's Yane Marques and Amelie Caze of France to finish second behind Lithuanian winner Laura Asadauskaite, the final gold medallist of the London Games.
Marques held on for the bronze but there was disappointment for Britain's world champion Mhairi Spence, who had a difficult day and finished 28th.
The action began in the Copper Box with the fencing, an event where Spence usually excels, living up to her nickname 'Fencey Spencey'. She won 19 of her 35 bouts for 856 points, which put her tied for 11, while Murray had the worst possible start, losing her first seven fights, but she recovered impressively and ended the fencing only one win behind Spence in joint 16th.
Her strongest, the 200 metres freestyle swim, came next, and Murray did not disappoint, posting a time of two minutes 08.20 seconds and her score of 1264 was enough to move her up to third place.
Spence was a couple of seconds off her best but posted a decent time of 2:16.51, climbing to ninth.
The show jumping can be a game changer, with riders paired with their horses at random and given only 20 minutes to acquaint themselves with their animal. The course proved tricky for nearly all the riders but Spence, who is a good rider, was unlucky to draw a particularly feisty horse and her score of 1096 points dropped her back down the field.
Murray also had some dramatic moments but without the costly consequences and her score of 1140 points kept her right in the hunt.
Murray told BBC1: "I had a lot to make up on so I needed that run. I've made a few mistakes today which set me back in the field but I came through in the end and my shooting was reasonably good as well. I'm just so pleased. My legs kept running for me and I'm so happy. The hills as well were so steep and I just kept working really hard."