To obtain the Missing: Shane lost and found quest in Dead Island 2, interact with the missing board in the Serling Hotel on Ocean Avenue. For this quest, you’re looking for Shane, a lifeguard who went missing at Venice Beach. Make your way to the southern part of Venice Beach to the lifeguard hut.
Inside collect the Offer of a Lifetime journal from the counter. It’ll tell you to go to the lifeguard hut on the other side of the beach. Head on over then clear out the zombies around it. A named lifeguard zombie will spawn. Take her out then collect the For Whom the Nell Tolls journal from where she falls.
Next, travel to the Lifeguard HQ at the Santa Monica Pier. Head to the southern side of HQ to find TJ the Lifeguard.
Take him out to complete the quest. As a reward, you’ll receive 2,000 XP.