I was able to get the first 3 chapters of Pretty Little Liars #10: Ruthless from Alloy Entertainment website.

The book started by what happened to the four girls after Twisted. Aria was hesitant to go on vacation in Iceland with Noel, Mike and Hanna. Later on, Aria saw Noel assisting Klaudia. She haven't speak with him for weeks after Klaudia's fall. Aria was so surprised that Noel approached her only to find out that he wanted to break things off between them. Emily, on the other hand, stayed at Carolyn's dorm. She was there for the whole summer because she had to hide from her parents due to her pregnancy issues. When she got back to her house, she was amazed that her older sister, Beth, was at there house. She noticed that her sister changed from being a obedient daughter to a rebel. And Spencer was involved in a drug incident. She needed to get out of this drug incident so she asked Hanna's help to frame up Kelsey. Spencer also had to deal with her mother's new relationship with Mr. Pennythistle. She was devastated that her parent's marriage ended to divorce. Good thing, her relationship with Melissa isn't about rivalry anymore. They're as close as any sisters can be but Spencer wanted to move out of their house. So when she got a mail from Princeton, she hoped for an early acceptance. But boy, Spencer was surprise that her future wasn't so secured. There were two Spencer Hastings who applied in Princeton and Spencer is still in a waiting list.

This is just a summary of the first 3 chapters. The book is not out yet. So I can't tell yet if the book is that great. But I've always been a PLL fan and I hope this will turn out great.

UPDATE:
I'm gonna spoil everything but the girls unearthed a mystery about Tabitha. And Kelsey, she's more to what she seems. The book revolved around her.

Basically, the book was about Spencer and how she dealt with her Kelsey guilt. Kelsey turned out to be a possible "A" suspect. Upon Spencer's investigation, Kelsey was in Jamaica the same time they killed Tabitha. Emily, on the other hand, met Kay aka Kelsey at a party and couldn't believe Spencer's accusations. She told Kelsey about how Spencer framed her up. Then, remember Hanna's dad for running for Congress? He has this rival, Mr. Wilkinson, whose son became Hanna's boyfriend. Hanna discovered Liam is a player and she's planning for revenge. OH MY, it's Aria's story next. She's my favorite among the girls. Well, Ezra returned. He returned and promised Aria everything. He wrote a novel for her which insinuated a fight. They were at Wordsmith's when Klaudia accidentally walked in on them. Aria introduced Klaudia to him. After some time, she caught them together. She was so devastated but then Noel came back. He said he's sorry for what he did to Aria and he, FINALLY, realized how devious Klaudia was. Klaudia was a klepto and Noel was weirded out by how Klaudia wanted to sleep with him. Noel expressed how he missed Aria and their cooking class. And they got back together. YEHEY! As for Kelsey, she went nuts and entered the Preserve. And I won't say this for thrill. They unearthed a mystery about Tabitha Clark!