novel by Alistair MacLean
The San Andreas is a WW2 Merchant Marine hospital ship in the Arctic. What the crew doesn't know is that it is loaded with gold. Unfortunately, the Germans do know. The undergunned, underprotected ship spends the book under attack from the air, under the sea, and from at least one saboteur (nicknamed flannelfoot) on board. Of all MacLean's books it reminds me the most of H.M.S. Ulysses, with a similar setting. The tone is not nearly as dark, however.
In the prologue MacLean fills in some background about the Merchant Marine. The living conditions were inhuman, the death rate was 47% higher than the national average, and if their ships were sunk their contracts were ended, so if they survived, they were fired... These men were truly unsung heroes, and San Andreas sings a little for them.