How can you explain a disappearance when everyone denies it happened?

Recently widowed Suzy Kemp decides to downsize to an independent-living apartment in a retirement community. But when she goes in for her final health screening, she becomes confused and is abruptly confined to a memory care unit . . . with no way out. What's worse, she suspects the late-night departure of another resident has a sinister cause. No one takes her suspicions seriously, so she's determined to investigate on her own, to uncover what happened to her neighbor and to prove she hasn't lost her mind.