SPOLIER
Ali had a twin sister Courtney, who Ali's parents wanted to keep a sercet. Courtney always wanted Ali's life because she (Courtey) was mental ill. So when the PLL's (aria, hanna, Emily and Spencer) came over to steal the flag Courtney, became friends with them because she couldn't be friends with Naomi and Riley. Ali had to be Courtney, so she killed her the night Ali (Countney) went missing.
The PLL's soon met Courtney (real ALi) who told them she was the real Ali and always their bestie. (Which was a lie) She took them to her summer home and tryed to kill them.
They all wonder because Ali coudn't have left alive but they never found her body. She also killed Jenna and Ian, they knew about the switch. So we wonder
Is she alive...
season 2 of pretty little liars will end on august, 10, 2011
No
hopefully
I believe it was the third book, and if not it is might be two, but he kills himself.
All of the messages from book one to book four excluding the "What Happens Next..." in the end of book four.
The books answer it.
A, it' all A! xx
Season 5
Not soon enough...
No one knows... :(
They didn't. It's still going.
They almost do expect in the shows they give more detail