Joss was born on the borders of East London and Essex. Leaving Essex behind for Cambridge, she went on to have careers in British diplomacy, as a policy adviser for Oxfam and along the way gained a doctorate in English Literature from Oxford University. More recently she has written for children and young adults, winning awards in both categories. She has published over fifty novels that have been translated into many languages. She lives in Oxford. Don't Trust Me is her debut novel for adults.