HarperCollins £17.99 pp465

There are two mysteries in this novel: the identity of a 200-year-old corpse, and why its discovery on a Lake District hillside triggers a series of murders. The appearance of the body revives a local legend, according to which Fletcher Christian, the man who led the mutiny on the Bounty, later faked his death on Pitcairn Island in order to return to England. Strange tattoos, usually seen on the bodies of sailors who spent time in the South Seas, convince Jane Gresham, a Wordsworth scholar, that the corpse may be that of Christian. Gresham is not the only one to whom this theory occurs but for her it has an added twist, connected to a letter she has found in the archive at Wordsworth’s home, Dove Cottage.

Given the documented family connections between the Wordsworths and the Christians, Gresham suspects that Fletcher secretly visited the poet on his return to England, pouring out a dramatic story that Wordsworth turned into an epic poem. While a pathologist carries out tests on the corpse, Gresham rushes from London to the Lake District, hot on the trail of what might be Wordsworth’s last and greatest work.

Before she leaves the rough council estate where she lives, she tries to help a bright mixed-race girl who has been threatened with sexual assault. When Gresham’s intervention goes wrong, the girl is suspected of murder and follows her to the Lake District. There Gresham is already being stalked by a former lover who also wants the priceless Wordsworth manuscript.

The Grave Tattoo is nothing like as gory as some McDermid novels, but it is ambitious. The chapters are interspersed with extracts from Christian’s secret diary that appear to confirm Gresham’s theory about the corpse, and there is a huge cast of characters. Gresham is assisted by Dan, a gay friend, and there are sub-plots about their love lives and Gresham’s edgy relationship with her brother.

No sooner have she and Dan worked out that the manuscript may be in the hands of a descendant of Wordsworth’s maid than elderly members of the family start dying. If this seems complicated, it also means McDermid has given herself too many plot strands to follow and the characters are lightly sketched rather than fully drawn.

She reserves her passion for the landscape, forgetting to inject it into the novel’s bad guys who either fail to scare or have a completely implausible heart of gold. Perhaps the absence of suspense arises from our knowledge that no such Wordsworth manuscript exists, lending a certain inevitability to the ending. But the process of getting there feels unduly drawn out, creating what seems more like episodes from a soap opera than a coherent detective novel.

Available at the Books First price of £16.19 on 0870 165 8585

Times Recommends

• The 100 Best Books of the Decade
• The Times picks the 50 best paperbacks of 2009
• The conversation: James Ellroy