Witty, chaotic MARNIE has been plagued by disturbing sexual thoughts for as long as she can remember. At the end of her rope, Marnie jumps on a bus to London on a mission to change her life.

Marnie hits another dead end when she goes to a sex addict’s meeting but it still doesn’t explain what’s wrong with her. Things start to look up when she finds an unexpected kindred spirit.

Marnie is determined to make the most of being a single Londoner now she knows what is wrong with her. She jumps into bed with Benji - an earnest, clingy barista.

Marnie and Charlie try to pick themselves back up after hitting rock-bottom. Marnie gets help from an unexpectedly understanding Shereen while Charlie tries to prove he’s up to his old job.

Helen, Marnie’s best friend from Scotland, is visiting London and Marnie is terrified of the sexual things that pop into her head when she is around.

Marnie is shaken to the core when she realises she’s pushed Shereen too far and starts to become paranoid that everyone has turned against her now they know about her condition.