J.K. Rowling is set to release her second novel under the pen name Robert Galbraith.

The 'Harry Potter' author wrote her first novel, 'The Cuckoo's Calling', under the alias last year and she's now working on a sequel to the bestselling crime novel, called 'Silkworm', which will be released later this year, according to publishers.

The 48-year-old writer had aimed to keep her crime writing venture a secret but her solicitor at the time revealed her pen name to the public and has since been fined and ordered to pay Rowling damages - which she donated to charity.

'Silkworm' will be the author's third book for adults, as she also released 'Casual Vacancy' under her real name in 2012.

Her newest crime story will feature private detective Cormoran Strike - who first appeared in 'The Cuckoo's Calling' - and he, along with his assistant Robin Ellacott, will unravel the death of writer Owen Quine after being hired by his wife to investigate his disappearance.

Rowling's publisher describes the novel as ''a compulsively readable crime novel with twists at every turn.''

The Scottish writer recently caused controversy by admitting she wasn't sure she was happy with the way in which she ended the final 'Harry Potter' book, and suggested she thought she should've written the ending so that Harry ended up with Hermione Granger rather than his best friend Ron Weasley, who married her instead.