Showing Mrs. Pollifax and the Golden Triangle by Dorothy Gilman

Resolved to give up spying for good, Mrs Pollifax can’t stop herself agreeing to carry a small object to an agent in Thailand, and get one in return.

The moment she lands, Mrs P. is horrified to find her contact dead and her husband kidnapped. The next thing she knows, she’s tramping through the unfamiliar Thai countryside, led by a curious fellow who may be trying to help her find her husband.

Or he may have other, more sinister plans ...

Armed with only an open mind and a little karate, Mrs Pollifax is the most unlikely and lovable of international spies.