Context: At the Kibbutz Stein in Israel in 1956, school teacher Rachel (Clarice van Houten) is reunited with Ronnie (Halina Reijn), a friend from The Hague during World War II. After Ronnie leaves, Rachel reflects on her adventures during the final days of the war.In 1944, Rachel hides from the Nazis in a farm in the Dutch countryside. In exchange for hiding her, they expect her to learn Bible verses. One day, a crippled Allied bomber drops its payload on the farmhouse, killing everyone except Rachel. Rob (Michiel Heisman), a young man from a neighboring farm, hides her in the family's greenhouse. That night, Van Gein (Peter Blok), a police officer, arrives to tell them that the Nazis know that Rachel is in the area and will hunt her down. He agrees to help Rachel and Rob escape to the Allied controlled southern part of Holland. Rachel visits her father's lawyer, Smaal (Dolf de Vries). He gives her enough money and jewels to live on for a year but warns her not to trust people so easily. Van Gein leads Rachel and Rob to a dock where other Jews wait to leave. Rachel is reunited with her parents and brother, who is recovering from an emergency appendectomy. Van Gein does not accompany the Jews on the boat trip. That evening, the boat is ambushed by a Nazi patrol boat. The Nazis immediately open fire; only Rachel survives the massacre. Before drifting down the river, she sees the Nazis loot the corpses.Rachel is found by Resistance fighters who smuggle her into The Hague by disguising her as a typhoid victim and placing her in a coffin that if properly "sealed" has sizable air holes. She is taken to a soup kitchen run by another member of the Resistance, Gerben Kuipers (Derek de Lint) and given the new name of Ellis de Vries. Eventually she is made a part of the Resistance's plans to smuggle in British guns and rations. The smugglers are led by Hans Akkermans (Thom Hoffman), an expert marksman. He and Ellis are to pose as husband and wife so the Nazis will not search their luggage on the train; the luggage is actually full of weaponry. But when the Nazi soldiers on the train clearly do intend to search all baggage, a new plan is needed. Ellis takes the bags and enters a private compartment occupied by SD Colonel Muntze (Sebastian Koch). The Nazis don't search Muntze's compartment. Ellis and Muntze are clearly attracted to each other and she accepts an offer to visit him at his office. Hans is clearly jealous.A truck carrying the British guns crashes in front of the soup kitchen. Kuiper's son, Tim (Ronald Armbrust) was driving and is arrested by the Gestapo. While the others go into hiding, Ellis arranges a meeting with Muntze hoping that she can persuade him to release Tim. Knowing he is an avid stamp collector, she takes some rare Dutch stamps to him. He invites her to a Nazi party. There she sees SS commandant Gunter Franken (Waldemar Kobus) and recognizes him as the Nazi who led the ambush against the refugee boat. Although she is sickened at his sight, she manages to sing at the party later. She and Muntze return to his suite to make love. He intuits that she is Jewish from her dyed blond hair but has fallen in love with her. She accepts a job in his office and begins work the following day. There she meets Ronnie, who is Franken's secretary/sex partner. Franken gives them a report indicating that Tim has confessed everything and is to be executed, however, Muntze refuses to sign the execution order.Ellis sees Smaal at Nazi headquarters and learns that he and Muntze have negotiated a cease fire -- if the Resistance ceases its attacks against the Nazis, the Nazis will cease its violent reprisals against Dutch civilians. However, when a hidden microphone placed by Ellis in Franken's office reveals that Franken and Van Gein have been working together to kill and rob Jews trying to escape into Allied territory, a controversy amongst the Resistance fighters ensues. Van Gein is heard 
 Question: What device does Ellis plant in Franken's office?
Output: a hidden microphone