A Struggle for Existence is the fifth Charles Darwin memory: Florence Nightingale tells you a policeman has hauled Darwin away, and the two of you go after him. You kidnap the officer for answers, then fight through a Templar hideout while Nightingale treats Darwin.
Part 5 of 6 in Charles Darwin's London Stories
Nightingale remembers the policeman mentioning a funeral and leads you there. Kidnap him and walk him to her; he admits a man paid him to bring Darwin to a secret base, then runs. Drive Nightingale to the base, clear it of Templars and find Darwin on a bed upstairs. Hold off the attackers while she stabilises him, then carry him down past a second group of Templars and put him in the carriage.
Meet Nightingale, follow her to the funeral, kidnap the corrupt policeman unseen, bring him to her, drive to the base, defeat the Templars, protect Nightingale while she works and carry Darwin out.
Both twins visit Darwin once he has recovered. Nightingale is sending him to his family on the Isle of Wight to rest; he plans to start his next book instead, and thanks the twins before he leaves.
Full sync only cares about the kidnapping, so reach the policeman at the funeral without being spotted, grab him and walk him back to Nightingale at a calm pace. The fights inside the Templar base come afterwards and carry no stealth condition.
Nightingale is outraged that an old man was dragged off like a common criminal and worries Darwin is no longer the fit young traveller he once was. She insists on entering the base with you, brushes off the twin's objection, and treats Darwin's wounds before she lets you move him.
An Abominable Mystery
An Abominable Mystery is the second Charles Darwin memory: a plant no botanist recognises is making people in a Westminster park delirious. You investigate the flower beds, follow tracks to a cart full of the plants and then use their pollen against pursuers while driving Darwin to a safe disposal spot.
Cruel Caricature
Cruel Caricature is the fourth Charles Darwin memory: posters showing Darwin as an ape under the slogan "We are not apes" are going up around London. You tear them down, catch a billposter and follow the trail to an underground print shop that you blow up.
Darwin's Orchid
Darwin's Orchid is a short Charles Darwin memory from The Darwin and Dickens Conspiracy: a rare orchid from Madagascar is waiting for Darwin at the docks, and a rival has sent thugs to take it first. You race across the river, grab the flower off a boat and bring it back.
Defamation
Defamation is a short Charles Darwin memory: Darwin asks you to fetch him a newspaper, and you find a Blighter bullying the newsboy. A foot chase follows, and the thug's leaflet shows that someone is paying to spread attacks on Darwin.