Complex sentence: W.I.T.C.H. After this success, Elisabetta began work again in 2005, when she published "The Secret of the Twins", which was developed into a trilogy focused around the magical world Fairy Oak.
Split into simpler sentences: W.I.T.C.H. After this success, Elisabetta published "The Secret of the Twins" in 2005. The book was developed into a trilogy focused around the magical world Fairy Oak.