Per­son­al nar­ra­tives and tes­ti­mo­ny help us piece togeth­er the sto­ries and events of the Holo­caust, whose lethal fin­gers reached into almost every cor­ner of Europe. How­ev­er, diaries and let­ters have an imme­di­a­cy that is shock­ing in their hon­esty, sus­pense, and irony. Hid­den Let­ters, orig­i­nal­ly pub­lished in Dutch in 1999, is a trea­sure trove of 86 let­ters and post­cards that a young Jew­ish man, Flip (Philip) Sli­er, wrote from April 25 to Sept. 14, 1942, in the labor camp of Molen­goot in north­east­ern Nether­lands. In a let­ter dat­ed June 3, 1942, Flip wrote: ​“Pa, you can safe­ly keep the let­ters. Put them in a cor­ner some­where, nobody will notice.” He was very much mis­tak­en. Because Flip was still a teenag­er while in Molen­goot, his ear­ly let­ters read rather like let­ters from sum­mer camp. He writes about pranks, like play­ing ghost or throw­ing water on someone’s bed. Under­neath the light tone, how­ev­er, one can sense a young man who worked ter­ri­bly hard, who was pro­vid­ed with inad­e­quate food and cloth­ing, who was try­ing to stay cheer­ful for his par­ents’ sakes. Lit­tle did he know that these camps were hold­ing pens for West­er­bork tran­sit camp, and ulti­mate­ly to con­cen­tra­tion camps like Auschwitz and Sobi­bor. Hid­den Let­ters is not only a col­lec­tion of let­ters writ­ten by Flip Sli­er, as heartrend­ing as they are. The edi­tors accom­pa­ny their exten­sive anno­ta­tions with over 200 pho­tographs, maps, doc­u­ments, realia (like stamps, ration cards, coins, stick­ers), posters, a fam­i­ly tree, lists of peo­ple men­tioned, as well as thor­ough bib­li­o­graph­i­cal ref­er­ences and an illus­trat­ed index. All this detailed infor­ma­tion reflects the anguish and courage of the peo­ple of occu­pied Hol­land. Flip’s ordeal is placed in a broad­er his­tor­i­cal con­text through rel­e­vant arti­cles, for exam­ple, the Jew­ish coun­cil in Ams­ter­dam, Mau­thausen con­cen­tra­tion camp, and Sobi­bor. The design of this book is stun­ning. The lay­out of let­ters, pho­tos, and oth­er doc­u­ments is log­i­cal and attrac­tive; the mar­gins, gen­er­ous; the fonts, clear and read­able. Anoth­er book about young peo­ple incar­cer­at­ed in Ger­man labor camps, enti­tled Sala’s Gift, by Ann Kirschn­er, is an engross­ing nar­ra­tive. This one is a fas­ci­nat­ing doc­u­men­tary. Both are heart­break­ing and inspiring.