Dell #350, It Ain't Hay by David Dodge Mapback - VG Condition

The edition
The novel's publishing history runs from Blue Book Magazine (Nov. 1946) to Simon and Schuster in 1946, a Unicorn Press edition in 1947, and then Dell in 1949 as #270, later reissued as #350. So your #350 is technically the second Dell paperback printing, not the first; at least one dealer describes it as the 2nd paperback edition from Dell (#350), 1949. It runs 192 pages at roughly 4.25 x 6.5 inches. The "With Crime Map on Back Cover" line on the front refers to the illustrated map of the story's locations, the feature that gives mapbacks their name and collector appeal. In the UK it was retitled A Drug on the Market (Michael Joseph, 1949).  

VERY GOOD CONDITION, still a little gloss (see pictures)

The cover art
The cover painting is by Gerald Gregg, Dell's house artist in that period. His airbrushed, surreal style is on full display here: the smoky ghost woman rising from the oversized cigarette, and the Grim Reaper rowing a coffin. The joke is in the title, since "hay" was period slang for marijuana, so that cigarette is a reefer. The keyhole-and-eye logo at bottom left is Dell's classic mystery emblem.

The story
It's the last of four novels Dodge wrote about hard-boiled San Francisco tax accountant-turned-detective James "Whit" Whitney, who first appeared in 1941's Death and Taxes. In this one, Whit lands in the crosshairs of a marijuana smuggling ring operating out of Half Moon Bay on fishing boats that run to Mexico. The Dodge companion site notes that the book marks his shift away from screwball mystery and Thin Man comparisons toward a more hard-boiled approach, with much of the Whit-and-Kitty banter gone; with Whit's descent into drugs, revenge, and infidelity, it's called Dodge's darkest novel.