First appeared in Alfred Hitchcock's Mystery Magazine. September 1986.
Also available in Trouble is What I Do by Rob Kantner, PointBlank, 2005.
A man calls from Guam asking for Gail. Ben Perkins tells the man he's dialed the wrong number. That night the same man calls back wanting to hire Perkins to find Gail in Cincinnati. Identifying himself as Paul Murray, he says Gail is his wife whom he left eight years earlier and now hopes to win back. Perkins is almost certain he's been lied to, but he's also overdrawn at the bank, so he takes the case.
Kantner takes full advantage of Perkins's being hired over the phone. It turns out almost none of Murray's story is true, and he succeeds in using Perkins to achieve goals that are likewise less than honest. By the same token, Perkins's accessibility, humanity, and everyman dilemmas are what distinguish him in a crowded P.I. field.
Trouble is What I Do collects 18 Perkins stories, each with an afterword from Kantner discussing what inspired him. Kantner was also kind enough to chat with DetecToday members last year. You can read the transcript here.